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  • global variables doesn't change value in Javascript

    - by user1856906
    My project is composed by 2 html pages: 1)index.html, wich contains the login and the registration form. 2)user_logged.html, wich contains all the features of a logged user. Now, what I want to do is a control if the user is really logged, to avoid the case where a user paste a url in the browser and can see the pages of another user. hours as now, if a user paste this url in the browser: www.user_loggato.html?user=x#profile is as if logged in as user x and this is not nice. My html pages both use js files that contains scripts. I decided to create a global variable called logged inizialized to false and change the variable to true when the login is succesfull. The problem is that the variable, remains false. here is the code: var logged=false; (write in the file a.js) while in the file b.js I have: function login() { //if succesfull logged=true; window.location.href = "user_loggato.html?user="+ JSON.parse(str).username + #profilo"; Now with some alerts I found that my variable logged is always false. Why? if I have not explained well or if there is not some information in order to respond to my question let me know.

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  • How to update csv column names with database table header

    - by user1523311
    I am facing this problem some past days and now frustrate because I have to do it. I need to update my CSV file columns name with database table header. My database table fields are different from CSV file. Now the problem is that first I want to update column name of CSV file with database table headers and then import its data with field mapping into database. Please help me I don't know how I can solve this. This is my php code: $file = $_POST['fileName']; $filename = "../files/" . $file; $list = $_POST['str']; $array_imp = implode(',', $list); $array_exp = explode(',', $array_imp); $fp = fopen("../files/" . $file, "w"); $num = count($fp); for ($c = 0; $c < $num; $c++) { if ($fp[c] !== '') { fputcsv($fp, $array_exp); } } fclose($fp);

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  • Pass 2-dimensional array trough view

    - by Mikael
    Hi, I'm trying to print a 2-dimensional array but can't figure it out. My controller uses this code: public ActionResult Test(string str) { DateTimeOffset offset = new DateTimeOffset(DateTime.Now); offset = offset.AddHours(-5); string[,] weekDays = new string[7,2]; for (int i = 0; i < 7; i++) { weekDays[i,0] = String.Format("{0:yyyy-MM-dd:dddd}", offset); //Date weekDays[i,1] = String.Format("{0:dddd}", offset); //Text offset = offset.AddHours(24); } weekDays[0,1] = "Today"; ViewData["weekDays"] = weekDays; return View(); } Now I wan't to print this array of weekdays as a dropdown-list and i thought this would work: <% foreach (var item in (string[,])ViewData["weekDays"]) { %> <option value=" <%= item[0] %> "> <%= item[1] %> </option> <% } %> But that's not the case, this code output just the first char of the string. So anyone got a suggestion? Thanks! /M

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  • Python: How to transfer varrying length arrays over a network connection

    - by Devin
    Hi, I need to transfer an array of varying length in which each element is a tuple of two integers. As an example: path = [(1,1),(1,2)] path = [(1,1),(1,2),(2,2)] I am trying to use pack and unpack, however, since the array is of varying length I don't know how to create a format such that both know the format. I was trying to turn it into a single string with delimiters, such as: msg = 1&1~1&2~ sendMsg = pack("s",msg) or sendMsg = pack("s",str(msg)) on the receiving side: path = unpack("s",msg) but that just prints 1 in this case. I was also trying to send 4 integers as well, which send and receive fine, so long as I don't include the extra string representing the path. sendMsg = pack("hhhh",p.direction[0],p.direction[1],p.id,p.health) on the receive side: x,y,id,health = unpack("hhhh",msg) The first was for illustration as I was trying to send the format "hhhhs", but either way the path doesn't come through properly. Thank-you for your help. I will also be looking at sending a 2D array of ints, but I can't seem to figure out how to send these more 'complex' structures across the network. Thank-you for your help.

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  • User input being limited to the alphabet in python

    - by Danger Cat
    I am SUPER new to programming and have my first assignment coming up in python. I am writing a hangman type game, where users are required to guess the word inputted from the other user. I have written most of the code, but the only problem I am having is when users have to input the word, making sure it is only limited to the alphabet. The code I have so far is : word = str.lower(raw_input("Type in your secret word! Shhhh... ")) answer = True while answer == True: for i in range(len(word)): if word[i] not in ("abcdefghijklmnopqrstuvwxyz"): word = raw_input("Sorry, words only contain letters. Please enter a word ") break else: answer = False This works while I input a few tries, but eventually will either exit the loop or displays an error. Is there any easier way to use this? We've really only covered topics up to loops in class, and break and continue are also very new to me. Thank you! (Pardon if the code is sloppy, but as I said I am very new to this....)

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  • Matching a String and then incrementing a number within HTML elements

    - by Abs
    Hello all, I have tags in a html list, here is an example of two tags. <div class="tags"> <ul> <li> <a onclick="tag_search('tag1');" href="#">tag1 <span class="num-active">1</span></a> </li> <li> <a onclick="tag_search('tag2');" href="#">tag2 <span class="num-active">1</span></a> </li> </ul> </div> I would like to write a function that I can pass a string to, that will match the strings in the a hyperlink i.e. "tag1" or "tag2", if there is a match then increment the number in the span, if not then add a new li. The bit I am having trouble with is how do I search for a string in the div with class tags and then when I find a match identifying the element. I can't even do the first bit as I am use to using an ID or a Class. I appreciate any help on this using JQuery Thanks all Code so far function change_tag_count(item){ alert(item);//alerts the string test $.fn.searchString = function(str) { return this.filter('*:contains("' + item + '")'); }; if($('body').searchString(item).length){ var n = $('a').searchString(item).children().text(); n = parseInt(n) + 1; $('a').searchString(item).children().text(n); }else{ alert('here');//does not alert this when no li contains the word test $("#all_tags ul").append('<a onclick="tag_search(\''+item+'\');" href="#">'+item+'<span class="num-active">1</span></a>'); } }

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  • matching images inside a link in regex

    - by user225269
    What is wrong with regex pattern that I created: $link_image_pattern = '/\<a\shref="([^"]*)"\>\<img\s.+\><\/a\>/'; preg_match_all($link_image_pattern, $str, $link_images); What I'm trying to do is to match all the links which has images inside of them. But when I try to output $link_images it contains everything inside the first index: <pre> <?php print_r($link_images); ?> </pre> The markup looks something like this: Array ( [0] = Array ([0] = " <p>&nbsp;</p> <p><strong><a href="url">Title</a></strong></p> <p>Desc</p> <p><a href="{$image_url2}"><img style="background-image:none;padding-left:0;padding-right:0;display:inline;padding-top:0;border-width:0;" title="image" border="0" alt="image" src="{$image_url2}" width="569" height="409"></a></p> But when outputting the contents of the matches, it simply returns the first string that matches the pattern plus all the other markup in the page like this: <a href="{$image_url}"><img style="background-image:none;padding-left:0;padding-right:0;display:inline;padding-top:0;border-width:0;" title="image" border="0" alt="image" src="{$image_url}" width="568" height="347"></a></p> <p>&nbsp;</p> <p><strong><a href="url">Title</a></strong></p> <p>Desc</p> <p><a href="{$image_url2}"><img style="background-image:none;padding-left:0;padding-right:0;display:inline;padding-top:0;border-width:0;" title="image" border="0" alt="image" src="{$image_url2}" width="569" height="409"></a></p>")

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  • Type contraint problem of C#

    - by user351565
    I meet a problem about type contraint of c# now. I wrote a pair of methods that can convert object to string and convert string to object. ex. static string ConvertToString(Type type, object val) { if (type == typeof(string)) return (string)val; if (type == typeof(int)) return val.ToString(); if (type.InSubclassOf(typeof(CodeObject))) return ((CodeObject)val).Code; } static T ConvertToObject<T>(string str) { Type type = typeof(T); if (type == typeof(string)) return (T)(object)val; if (type == typeof(int)) return (T)(object)int.Parse(val); if (type.InSubclassOf(typeof(CodeObject))) return Codes.Get<T>(val); } where CodeObject is a base class of Employees, Offices ..., which can fetch by static method Godes.Get where T: CodeObject but the code above cannot be compiled because error #CS0314 the generic type T of method ConvertToObject have no any constraint but Codes.Get request T must be subclass of CodeObject i tried use overloading to solve the problem but not ok. is there any way to clear up the problem? like reflection?

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  • Python OOP - object has no attribute

    - by user1744269
    I am attempting to learn how to program. I really do want to learn how to program; I love the building and design aspect of it. However, in Java and Python, I have tried and failed with programs as they pertain to objects, classes, methods.. I am trying to develop some code for a program, but im stumped. I know this is a simple error. However I am lost! I am hoping someone can guide me to a working program, but also help me learn (criticism is not only expected, but APPRECIATED). class Converter: def cTOf(self, numFrom): numFrom = self.numFrom numTo = (self.numFrom * (9/5)) + 32 print (str(numTo) + ' degrees Farenheit') return numTo def fTOc(self, numFrom): numFrom = self.numFrom numTo = ((numFrom - 32) * (5/9)) return numTo convert = Converter() numFrom = (float(input('Enter a number to convert.. '))) unitFrom = input('What unit would you like to convert from.. ') unitTo = input('What unit would you like to convert to.. ') if unitFrom == ('celcius'): convert.cTOf(numFrom) print(numTo) input('Please hit enter..') if unitFrom == ('farenheit'): convert.fTOc(numFrom) print(numTo) input('Please hit enter..')

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  • Shell halts while looping and 'transforming' values in dictionary (Python 2.7.5)

    - by Gus
    I'm building a program that will sum digits in a given list in a recursive way. Say, if the source list has 10 elements, the second list will have 9, the third 8 and so on until the last list that will have only one element. This is done by adding the first element to the second, then the second to the third and so on. I'm stuck without feedback from the shell. It halts without throwing any errors, then in a couple of seconds the fan is spinning like crazy. I've read quite a few posts here and changed my approach, but I'm not sure that what have so far can produce the results I'm looking for. Thanks in advance: #--------------------------------------------------- #functions #--------------------------------------------------- #sum up pairs in a list def reduce(inputList): i = 0 while (i < len(inputList)): #ref to current and next item j = i + 1 #don't go for the last item if j != len(inputList): #new number eq current + next number newNumber = inputList[i] + inputList[j] if newNumber >= 10: #reduce newNumber to single digit newNumber = sum(map(int, str(newNumber))) #collect into temp list outputList.append(newNumber) i = i + 1 return outputList; #--------------------------------------------------- #program starts here #--------------------------------------------------- outputList = [] sourceList = [7, 3, 1, 2, 1, 4, 6] counter = len(sourceList) dict = {} dict[0] = sourceList print '-------------' print 'Level 0:', dict[0] for i in range(counter): j = i + 1 if j != counter: baseList = dict.get(i) #check function to understand what it does newList = reduce(baseList) #new key and value from previous/transformed value dict[j] = newList print 'Level %d: %s' % (j, dict[j])

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  • Encouter error "Linux ip -6 addr add failed" while setting up OpenVPN client

    - by Mickel
    I am trying to set up my router to use OpenVPN and have gotten quite far (I think), but something seems to be missing and I am not sure what. Here is my configuration for the client: client dev tun proto udp remote ovpn.azirevpn.net 1194 remote-random resolv-retry infinite auth-user-pass /tmp/password.txt nobind persist-key persist-tun ca /tmp/AzireVPN.ca.crt remote-cert-tls server reneg-sec 0 verb 3 OpenVPN client log: Nov 8 15:45:13 rc_service: httpd 15776:notify_rc start_vpnclient1 Nov 8 15:45:14 openvpn[27196]: OpenVPN 2.3.2 arm-unknown-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL] [MH] [IPv6] built on Nov 1 2013 Nov 8 15:45:14 openvpn[27196]: NOTE: the current --script-security setting may allow this configuration to call user-defined scripts Nov 8 15:45:14 openvpn[27196]: Socket Buffers: R=[116736->131072] S=[116736->131072] Nov 8 15:45:14 openvpn[27202]: UDPv4 link local: [undef] Nov 8 15:45:14 openvpn[27202]: UDPv4 link remote: [AF_INET]178.132.75.14:1194 Nov 8 15:45:14 openvpn[27202]: TLS: Initial packet from [AF_INET]178.132.75.14:1194, sid=44d80db5 8b36adf9 Nov 8 15:45:14 openvpn[27202]: WARNING: this configuration may cache passwords in memory -- use the auth-nocache option to prevent this Nov 8 15:45:14 openvpn[27202]: VERIFY OK: depth=1, C=RU, ST=Moscow, L=Moscow, O=Azire Networks, OU=VPN, CN=Azire Networks, name=Azire Networks, [email protected] Nov 8 15:45:14 openvpn[27202]: Validating certificate key usage Nov 8 15:45:14 openvpn[27202]: ++ Certificate has key usage 00a0, expects 00a0 Nov 8 15:45:14 openvpn[27202]: VERIFY KU OK Nov 8 15:45:14 openvpn[27202]: Validating certificate extended key usage Nov 8 15:45:14 openvpn[27202]: ++ Certificate has EKU (str) TLS Web Server Authentication, expects TLS Web Server Authentication Nov 8 15:45:14 openvpn[27202]: VERIFY EKU OK Nov 8 15:45:14 openvpn[27202]: VERIFY OK: depth=0, C=RU, ST=Moscow, L=Moscow, O=AzireVPN, OU=VPN, CN=ovpn, name=ovpn, [email protected] Nov 8 15:45:15 openvpn[27202]: Data Channel Encrypt: Cipher 'BF-CBC' initialized with 128 bit key Nov 8 15:45:15 openvpn[27202]: Data Channel Encrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Nov 8 15:45:15 openvpn[27202]: Data Channel Decrypt: Cipher 'BF-CBC' initialized with 128 bit key Nov 8 15:45:15 openvpn[27202]: Data Channel Decrypt: Using 160 bit message hash 'SHA1' for HMAC authentication Nov 8 15:45:15 openvpn[27202]: Control Channel: TLSv1, cipher TLSv1/SSLv3 DHE-RSA-AES256-SHA, 2048 bit RSA Nov 8 15:45:15 openvpn[27202]: [ovpn] Peer Connection Initiated with [AF_INET]178.132.75.14:1194 Nov 8 15:45:17 openvpn[27202]: SENT CONTROL [ovpn]: 'PUSH_REQUEST' (status=1) Nov 8 15:45:17 openvpn[27202]: PUSH: Received control message: 'PUSH_REPLY,ifconfig-ipv6 2a03:8600:1001:4010::101f/64 2a03:8600:1001:4010::1,route-ipv6 2000::/3 2A03:8600:1001:4010::1,redirect-gateway def1 bypass-dhcp,dhcp-option DNS 194.1.247.30,tun-ipv6,route-gateway 178.132.77.1,topology subnet,ping 3,ping-restart 15,ifconfig 178.132.77.33 255.255.255.192' Nov 8 15:45:17 openvpn[27202]: OPTIONS IMPORT: timers and/or timeouts modified Nov 8 15:45:17 openvpn[27202]: OPTIONS IMPORT: --ifconfig/up options modified Nov 8 15:45:17 openvpn[27202]: OPTIONS IMPORT: route options modified Nov 8 15:45:17 openvpn[27202]: OPTIONS IMPORT: route-related options modified Nov 8 15:45:17 openvpn[27202]: OPTIONS IMPORT: --ip-win32 and/or --dhcp-option options modified Nov 8 15:45:17 openvpn[27202]: TUN/TAP device tun0 opened Nov 8 15:45:17 openvpn[27202]: TUN/TAP TX queue length set to 100 Nov 8 15:45:17 openvpn[27202]: do_ifconfig, tt->ipv6=1, tt->did_ifconfig_ipv6_setup=1 Nov 8 15:45:17 openvpn[27202]: /usr/sbin/ip link set dev tun0 up mtu 1500 Nov 8 15:45:18 openvpn[27202]: /usr/sbin/ip addr add dev tun0 178.132.77.33/26 broadcast 178.132.77.63 Nov 8 15:45:18 openvpn[27202]: /usr/sbin/ip -6 addr add 2a03:8600:1001:4010::101f/64 dev tun0 Nov 8 15:45:18 openvpn[27202]: Linux ip -6 addr add failed: external program exited with error status: 254 Nov 8 15:45:18 openvpn[27202]: Exiting due to fatal error Any ideas are most welcome!

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  • How to set up Mod_WSGI for Python on Ubuntu

    - by AutomatedTester
    Hi, I am trying to setup MOD_WSGI on my Ubuntu box. I have found steps that said I needed to do the following steps I found at http://ubuntuforums.org/showthread.php?t=833766 sudo apt-get install libapache2-mod-wsgi sudo a2enmod mod-wsgi sudo /etc/init.d/apache2 restart sudo gedit /etc/apache2/sites-available/default and update the Directory <Directory /var/www/> Options Indexes FollowSymLinks MultiViews ExecCGI AddHandler cgi-script .cgi AddHandler wsgi-script .wsgi AllowOverride None Order allow,deny allow from all </Directory> sudo /etc/init.d/apache2 restart Created test.wsgi with def application(environ, start_response): status = '200 OK' output = 'Hello World!' response_headers = [('Content-type', 'text/plain'), ('Content-Length', str(len(output)))] start_response(status, response_headers) return [output] Step 2 fails because it says it can't find mod-wsgi even though the apt-get found it. If I carry on with the steps the python app just shows as plain text in a browser. Any ideas what I have done wrong? EDIT: Results for questions asked automatedtester@ubuntu:~$ dpkg -l libapache2-mod-wsgi Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Cfg-files/Unpacked/Failed-cfg/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name Version Description +++-======================================-======================================-============================================================================================ ii libapache2-mod-wsgi 2.5-1 Python WSGI adapter module for Apache automatedtester@ubuntu:~$ dpkg -s libapache2-mod-wsgi Package: libapache2-mod-wsgi Status: install ok installed Priority: optional Section: python Installed-Size: 376 Maintainer: Ubuntu MOTU Developers <[email protected]> Architecture: i386 Source: mod-wsgi Version: 2.5-1 Depends: apache2, apache2.2-common, libc6 (>= 2.4), libpython2.6 (>= 2.6), python (>= 2.5), python (<< 2.7) Suggests: apache2-mpm-worker | apache2-mpm-event Conffiles: /etc/apache2/mods-available/wsgi.load 06d2b4d2c95b28720f324bd650b7cbd6 /etc/apache2/mods-available/wsgi.conf 408487581dfe024e8475d2fbf993a15c Description: Python WSGI adapter module for Apache The mod_wsgi adapter is an Apache module that provides a WSGI (Web Server Gateway Interface, a standard interface between web server software and web applications written in Python) compliant interface for hosting Python based web applications within Apache. The adapter provides significantly better performance than using existing WSGI adapters for mod_python or CGI. Original-Maintainer: Debian Python Modules Team <[email protected]> Homepage: http://www.modwsgi.org/ automatedtester@ubuntu:~$ sudo a2enmod libapache2-mod-wsgi ERROR: Module libapache2-mod-wsgi does not exist! automatedtester@ubuntu:~$ sudo a2enmod mod-wsgi ERROR: Module mod-wsgi does not exist! FURTHER EDIT FOR RMYates automatedtester@ubuntu:~$ apache2ctl -t -D DUMP_MODULES apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1 for ServerName Loaded Modules: core_module (static) log_config_module (static) logio_module (static) mpm_worker_module (static) http_module (static) so_module (static) alias_module (shared) auth_basic_module (shared) authn_file_module (shared) authz_default_module (shared) authz_groupfile_module (shared) authz_host_module (shared) authz_user_module (shared) autoindex_module (shared) cgid_module (shared) deflate_module (shared) dir_module (shared) env_module (shared) mime_module (shared) negotiation_module (shared) python_module (shared) setenvif_module (shared) status_module (shared) Syntax OK automatedtester@ubuntu:~$

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  • why i failed to build vsftp?

    - by hugemeow
    make, then failed with the following message. the main point is /lib/libcap.so.1: could not read symbols: File in wrong format, confusing... gcc -c readwrite.c -O2 -Wall -W -Wshadow -idirafter dummyinc gcc -c opts.c -O2 -Wall -W -Wshadow -idirafter dummyinc gcc -c ssl.c -O2 -Wall -W -Wshadow -idirafter dummyinc gcc -c sslslave.c -O2 -Wall -W -Wshadow -idirafter dummyinc gcc -c ptracesandbox.c -O2 -Wall -W -Wshadow -idirafter dummyinc gcc -c ftppolicy.c -O2 -Wall -W -Wshadow -idirafter dummyinc gcc -c sysutil.c -O2 -Wall -W -Wshadow -idirafter dummyinc gcc -c sysdeputil.c -O2 -Wall -W -Wshadow -idirafter dummyinc gcc -o vsftpd main.o utility.o prelogin.o ftpcmdio.o postlogin.o privsock.o tunables.o ftpdataio.o secbuf.o ls.o postprivparent.o logging.o str.o netstr.o sysstr.o strlist.o banner.o filestr.o parseconf.o secutil.o ascii.o oneprocess.o twoprocess.o privops.o standalone.o hash.o tcpwrap.o ipaddrparse.o access.o features.o readwrite.o opts.o ssl.o sslslave.o ptracesandbox.o ftppolicy.o sysutil.o sysdeputil.o -Wl,-s `./vsf_findlibs.sh` /lib/libcap.so.1: could not read symbols: File in wrong format collect2: ld returned 1 exit status make: *** [vsftpd] Error 1 [mirror@hugemeow vsftpd]$ ls /lib/libc libc-2.5.so libcap.so.1.10 libcidn.so.1 libcom_err.so.2.1 libcrypto.so.0.9.8e libcrypt.so.1 libcap.so.1 libcidn-2.5.so libcom_err.so.2 libcrypt-2.5.so libcrypto.so.6 libc.so.6 [mirror@hugemeow vsftpd]$ ls /lib/libc libc-2.5.so libcap.so.1.10 libcidn.so.1 libcom_err.so.2.1 libcrypto.so.0.9.8e libcrypt.so.1 libcap.so.1 libcidn-2.5.so libcom_err.so.2 libcrypt-2.5.so libcrypto.so.6 libc.so.6 [mirror@hugemeow vsftpd]$ ls /lib/libcap.so.1 -l lrwxrwxrwx 1 root root 14 Mar 20 2012 /lib/libcap.so.1 -> libcap.so.1.10 [mirror@hugemeow vsftpd]$ ls /lib/libcap.so.1 -lh lrwxrwxrwx 1 root root 14 Mar 20 2012 /lib/libcap.so.1 -> libcap.so.1.10 [mirror@hugemeow vsftpd]$ ls /lib/libcap.so.1 -lhL -rwxr-xr-x 1 root root 12K Mar 15 2007 /lib/libcap.so.1 this may have something to do with 64 bit system, but i have make modification to vsf_findlibs.sh 48 # Look for libcap (capabilities) 49 if locate_library /lib64/libcap.so.1; then 50 echo "/lib/libcap.so.1"; 51 elif locate_library /lib64/libcap.so.2; then 52 echo "/lib/libcap.so.2"; 53 else 54 # locate_library /usr/lib/libcap.so && echo "-lcap"; 55 # locate_library /lib/libcap.so && echo "-lcap"; 56 locate_library /lib64/libcap.so.1 && echo "-lcap"; 57 fi but make failed with the same error, why?

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  • Workaround with paths in vista

    - by Argiropoulos Stavros
    Not really a programming question but i think quite relative. I have a .exe running in my windows XP PC. This exe needs a file in the same directory to run and has no problem finding it in XP BUT in Vista(I tried this in several machines and works in some of them) fails to run. I'm guessing there is a problem finding the path.The program is written in basic(Yes i know..) I attach the code below. Can you think of any workarounds? Thank you The exe is located in c:\tools Also the program runs in windows console(It starts but then during the execution cannot find a custom file type .TOP made by the creator of the program) ' PROGRAMM TOP11.BAS DEFDBL A-Z CLS LOCATE 1, 1 COLOR 14, 1 FOR i = 1 TO 80 PRINT "±"; NEXT i LOCATE 1, 35: PRINT "?? TOP11 ??" PRINT " €€‚—‚„‘ ’— ‹„’†‘„— ‘’† „”€„€ ’†‘ ‡€€‘‘†‘ ‰€ † „.‚.‘.€. " COLOR 7, 0 PRINT "-------------------------------------------------------------------------------" PRINT INPUT "ƒ?©« «¦¤ ©¬¤«?©«? ¤???... : ", Factor# INPUT "¤¦£ ¨®e¦¬ [.TOP] : ", topfile$ VIEW PRINT 7 TO 25 file1$ = topfile$ + ".TOP" file2$ = topfile$ + ".T_P" file3$ = "Syntel" OPEN file3$ FOR OUTPUT AS #3 PRINT #3, " ‘¬¤«?©«?? ¤??? = " + STR$(Factor#) + " †‹„‹†€: " + DATE$ CLOSE #3 command1$ = "copy" + " " + file1$ + " " + file2$ SHELL command1$ '’¦ ¨®e¦ .TOP ¤« ¨a­«  £ «¤ ?«a?¥ .T_P OPEN file2$ FOR INPUT AS #1 OPEN file1$ FOR OUTPUT AS #2 bb$ = " \\\ \ , ###.#### ###.#### ####.### ##.### " DO LINE INPUT #1, Line$ Line$ = RTRIM$(LTRIM$(Line$)) icode$ = LEFT$(Line$, 1) IF icode$ = "1" THEN Line$ = " " + Line$ PRINT #2, Line$ PRINT Line$ ELSEIF icode$ = "2" THEN Line$ = " " + Line$ PRINT #2, Line$ PRINT Line$ ELSEIF icode$ = "3" THEN Number$ = MID$(Line$, 3, 6) Hangle = VAL(MID$(Line$, 14, 9)) Zangle = VAL(MID$(Line$, 25, 9)) Distance = VAL(MID$(Line$, 36, 9)) Distance = Distance * Factor# Height = VAL(MID$(Line$, 48, 6)) PRINT #2, USING bb$; icode$; Number$; Hangle; Zangle; Distance; Height PRINT USING bb$; icode$; Number$; Hangle; Zangle; Distance; Height ELSE END IF LOOP UNTIL EOF(1) VIEW PRINT CLS LOCATE 1, 1 PRINT " *** ’„‘ ’“ ‚€‹‹€’‘ *** " END

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  • adress-chunk: separate data stored in one collumn - into three (street, postal-code, town)

    - by zero
    hello dear community. Hello dear friends form all over the planet first of all - this is a great great forum. I like this place to share the ideas. It is so great to see such a supportive place - featuring the knowledge exchange! today i have the following thing to discuss: i want to separate the following data that are stored in one column of a calc-spreadsheet: See the following data: You see that there are the following categories:_ steet, postal-code, town All the data are stored in only one Colum; Well to be honest: i want to separate them into three colums steet, postal-code, town see the data: what can i do? note - you see that there are commas inbetween the enties: and besides this we see that we have a postal-code with four digits: that is a good thing. Perhaps we can use this as a marker that helps us to separate the data?! Perhaps See a data-sample! Here you can see some exceptions: eg. the town that has two words combinde with a "-" ... or somethims without any signs and characters... see the following... as an example: Max-Bader-Platz 1, 5620 Schwarzach im Pongau Pestalozzistraße 4, 9990 Nussdorf-Debant Schulstraße 4, 5162 Obertrum am See But i guess that this means no problem... What do you think about this? I am very very interested to get your opinion! i look forward to hear from you! regards see a snipped of the dataset - that is stored in one column -[b]Goal: [/b]i want to separate the datas into three collumns... : Schulweg 6, 9871 Seeboden Khevenhüllerstraße 45, 4861 Schörfling Franz Xaver Rennstr.18, 6460 Imst Schulstraße 4, 5162 Obertrum am See Schulweg 6, 7432 Oberschützen Pestalozzistraße 4, 9990 Nussdorf-Debant Niederndorf bei Kufstein 53c, 6342 Niederndorf bei Kufstein Hauptschulstraße 18, 2183 Neusiedl an der Zaya Seeweg 14, 5202 Neumarkt am Wallersee Europaplatz 1, 8820 Neumarkt in Steiermark Schulstraße 7, 4212 Neumarkt im Mühlkreis Schulstraße 20, 4720 Neumarkt im Hausruckkreis Bahnhofstr. 10, 4872 Neukirchen an der Vöckla Schulstraße 5b, 4780 Schärding Reitbergstraße 2, 4311 Schwertberg Europaplatz 1, 2320 Schwechat Am Schulberg 5, 3931 Schweiggers Waidach 8, 6130 Schwaz Waidach 8, 6130 Schwaz Max-Bader-Platz 1, 5620 Schwarzach im Pongau Markt 29, 2662 Schwarzau im Gebirge Hofsteigstraße 68, 6858 Schwarzach Gmundner Straße 7, 4690 Schwanenstadt Mühlfeldstraße 1, 4690 Schwanenstadt Mainsdorferstraße 18, 8541 Schwanberg Jakob Stemer-Weg 3, 6780 Schruns Obere Umfahrungsstraße 16, 2432 Schwadorf bei Wien Battloggstraße 54, 6780 Schruns Schloss-Straße 19, 5020 Salzburg Schillerplatz 2, 8280 Fürstenfeld Erzherzog-Johann-Str. 400, 8970 Schladming Schulgasse 261, 8811 Scheifling i look forward to hear from you!! regards

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  • Make mod_wsgi use python2.7.2 instead of python2.6?

    - by guron
    i am running Ubuntu 10.04.1 LTS and it came pre-packed with python2.6 but i need to replace it with python2.7.2. (The reason is simple, 2.7 has a lot of features backported from 3 ) i had installed python2.7.2 using ./configure make make altinstall the altinstall option installed it, without touching the system default version, to /usr/local/lib/python2.7 and placed the interpreter in /usr/local/bin/python2.7 Then to help mod_wsgi find python2.7 i added the following to /etc/apache2/sites-available/wsgisite WSGIPythonHome /usr/local i start apache and run a test wsgi app BUT i am greeted by python 2.6.5 and not Python2.7 Later i replaced the default python simlink to point to python 2.7 ln -f /usr/local/bin/python2.7 /usr/bin/python Now typing 'python' on the console opens python2.7 but somehow mod_wsgi still picks up python2.6 Next i tried, PATH=/usr/local/bin:$PATH export PATH then do a quick restart apache, but yet again its python2.6 !! Here is my $PATH /usr/local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games contents of /etc/apache2/sites-available/wsgisite WSGIPythonHome /usr/local <VirtualHost *:80> ServerName wsgitest.local DocumentRoot /home/wwwhost/pydocs/wsgi <Directory /home/wwwhost/pydocs/wsgi> Order allow,deny Allow from all </Directory> WSGIScriptAlias / /home/wwwhost/pydocs/wsgi/app.wsgi </VirtualHost> app.wsgi import sys def application(environ, start_response): status = '200 OK' output = sys.version response_headers = [('Content-type', 'text/plain'), ('Content-Length', str(len(output)))] start_response(status, response_headers) return [output] Apache error.log 'import site' failed; use -v for traceback [Sun Jun 19 00:27:21 2011] [info] mod_wsgi (pid=23235): Initializing Python. [Sun Jun 19 00:27:21 2011] [notice] Apache/2.2.14 (Ubuntu) mod_wsgi/2.8 Python/2.6.5 configured -- resuming normal operations [Sun Jun 19 00:27:21 2011] [info] Server built: Nov 18 2010 21:20:56 [Sun Jun 19 00:27:21 2011] [info] mod_wsgi (pid=23238): Attach interpreter ''. [Sun Jun 19 00:27:21 2011] [info] mod_wsgi (pid=23239): Attach interpreter ''. [Sun Jun 19 00:27:31 2011] [info] mod_wsgi (pid=23238): Create interpreter 'wsgitest.local|'. [Sun Jun 19 00:27:31 2011] [info] [client 192.168.1.205] mod_wsgi (pid=23238, process='', application='wsgitest.local|'): Loading WSGI script '/home/wwwhost/pydocs/$ [Sun Jun 19 00:27:50 2011] [info] mod_wsgi (pid=23239): Create interpreter 'wsgitest.local|'. Has anybody ever managed to make mod_wsgi run on a non-system default version of python ?

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  • Passing array values using Ajax & JSP

    - by Maya
    This is my chart application... <script type="text/javascript" > function listbox_moveacross(sourceID, destID) { var src = document.getElementById(sourceID); var dest = document.getElementById(destID); for(var count=0; count < src.options.length; count++) { if(src.options[count].selected == true) { option = src.options[count]; newOption = document.createElement("option"); newOption.value = option.value; newOption.text = option.text; newOption.selected = true; try { dest.add(newOption,null); //Standard src.remove(count,null); alert("New Option Value: " + newOption.value); } catch(error) { dest.add(newOption); // IE only src.remove(count); alert("success IE User"); } count--; } } } function printValues(oSel) { len=oSel.options.length; for(var i=0;i<len;i++) { if(oSel.options[i].selected) { data+="\n"+ oSel.options[i].text + "["+ "\t" + oSel.options[i].value + "]"; } } type=document.getElementById("typeId"); type_text=type.options[type.selectedIndex].text; type_value=document.getElementById("typeId").value; } function GetSelectedItem() { len = document.chart.d.length; i = 0; chosen = ""; for (i = 0; i < len; i++) { if (document.chart.d[i].selected) { chosen = chosen + document.chart.d[i].value + "\n" } } return chosen } $(document).ready(function() { var d; var current_month; var month; var str; var w; var sel; var sel_data; var sel_data_value; $('.submit').click(function(){ // to get current month d=new Date(); month=new Array(12); month[0]="January"; month[1]="February"; month[2]="March"; month[3]="April"; month[4]="May"; month[5]="June"; month[6]="July"; month[7]="August"; month[8]="September"; month[9]="October"; month[10]="November"; month[11]="December"; current_month=d.getMonth(); str=month[d.getMonth()]; w=document.chart.periodId.selectedIndex; // to get selected index value.... sel=document.chart.periodId.options[w].text; // to get selected index value text... for(i=sel;i>=1;i--) { alert(month[i]); } sel_data=document.chart.d.selectedIndex; sel_data_value=document.chart.d.options[sel_data].text; var data_len=document.chart.d.length; var j=0; var chosen=""; for(j=0;j<data_len;j++) { if(document.chart.d.options[i].selected) { chosen=chosen+document.chart.d.options[i].value; } } chart = new Highcharts.Chart({ chart: { renderTo: 'container', defaultSeriesType: 'column' }, title: { text: document.chart.chartTitle.value }, subtitle: { text: 'Source: WorldClimate.com' }, xAxis: { categories: month }, yAxis: { min: 0, title: {text: 'Count' } }, legend: { layout: 'vertical', backgroundColor: '#FFFFFF', align: 'left', verticalAlign: 'top', x: 100, y: 70, floating: true, shadow: true }, tooltip: { formatter: function() { return ''+ this.x +': '+ this.y +' mm'; } }, plotOptions: { column: { pointPadding: 0.2, borderWidth: 0 } }, series: [{ name: sel_data_value, data: [50, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4] }, { name: 'New York', data: [83.6, 78.8, 98.5, 93.4, 106.0, 84.5, 105.0, 104.3, 91.2, 83.5, 106.6, 92.3] }, { name: 'London', data: [48.9, 38.8, 39.3, 41.4, 47.0, 48.3, 59.0, 59.6, 52.4, 65.2, 59.3, 51.2] }, { name: 'Berlin', data: [42.4, 33.2, 34.5, 39.7, 52.6, 75.5, 57.4, 60.4, 47.6, 39.1, 46.8, 51.1] }] }); }); }); </script> <%! Connection con = null; Statement stmt = null; ResultSet rs = null; String url = "jdbc:postgresql://192.168.1.196:5432/autocube3"; String user = "autocube"; String pass = "autocube"; String query = ""; int mid; %> <% ChartCategory chartCategory = new ChartCategory(); chartCategory.setBar_name("vehicle reporting"); chartCategory.setMonth("3"); chartCategory.setValue("1000"); if (request.getParameter("mid") != null) { mid = Integer.parseInt(request.getParameter("mid")); } else { mid = 0; } Class.forName("org.postgresql.Driver"); con = DriverManager.getConnection(url, user, pass); System.out.println("Connected to Database"); stmt = con.createStatement(); rs = stmt.executeQuery("select code,description from plant"); %> </head> <body> <form method="post" name="chart"> <fieldset> <legend>Chart Options</legend> <br /> <!-- Plant Select box --> <label for="hstate">Plant:</label> <select name="plantId" size="1" id="plantId" > <!--onchange="selectPlant(this)" --> <% while (rs.next()) { %> <option value="<%=rs.getString("code")%>"><%=rs.getString("description")%></option> <% } String plant = request.getParameter("hstate"); System.out.println("Selected Plant" + request.getParameterValues("plantId")); %> </select> <br /> <label for="hcountry">Period</label> <select name="periodId" id="periodId"> <option value="0">1</option> <option value="1">2</option> <option value="2">3</option> <option value="3">4</option> <option value="4">5</option> <option value="5">6</option> <option value="6">7</option> <option value="7">8</option> <option value="8">9</option> <option value="9">10</option> <option value="10">11</option> <option value="11">12</option> </select> <br/> <!--Interval --> <label for="hstate" >Interval</label> <select name="intervalId" id="intervalId"> <option value="day">Day</option> <option value="month" selected>Month</option> </select> </fieldset> <fieldset> <legend>Chart Data</legend> <br/> <br/> <table > <tbody> <tr> <td> &emsp;<select multiple name="data" size="5" id="s" style="width: 230px; height: 130px;" > <% String[] list = ReportField.getList(); for (int i = 0; i < list.length; i++) { String field = ReportField.getFieldName(list[i]); %> <option value="<%=field%>"><%=list[i]%></option> <% //System.out.println("Names :" + list[i]); //System.out.println("Field Names :" + field); } %> </select> </td> <td> <input type="button" value=">>" onclick="listbox_moveacross('s', 'd')" /><br/> <input type="button" value="<<" onclick="listbox_moveacross('d', 's')" /> &emsp; </td> <td> &emsp; <select name="selectedData" size="5" id="d" style="width: 230px; height: 130px;"> </select></td> <% for (int i = 0; i <= 4; i++) { String arr = request.getParameter("selectedData"); System.out.println("Arrya" + arr); } %> </tr> </tbody> </table> <br/> </fieldset> <fieldset> <legend>Chart Info</legend> <br/> <label for="hstate" >Type</label> <select name="typeId" id="typeId"> <option value="" selected>select...</option> <option value="bar">Bar</option> <option value="pie" >Pie</option> <option value="line" >Line</option> </select> <br/> <label for="uname" id="titleId">Title </label> <input class="text" type="text" name="chartTitle"/> <br /> <label for="uemail2">Pin to Dash board:</label> <input class="text" type="checkbox" id="pinId" name="pinId"/> </fieldset> <input class="submit" type="button" value="Submit" /> <!--onclick="printValues(s)"--> </form> <div id="container" style="width: 800px; height: 400px; margin: 0 auto"> </div> </body> </html> using javascript function, am storing the selected listbox values in 'sel_data_value'. I need to pass this selected array values to database to retrieve values regarding selection. How can i do this using ajax. i don know how to pass array values in ajax and retrieve it from database. Thanks.

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  • file doesn't open, running outside of debugger results in seg fault (c++)

    - by misterich
    Hello (and thanks in advance) I'm in a bit of a quandry, I cant seem to figure out why I'm seg faulting. A couple of notes: It's for a course -- and sadly I am required to use use C-strings instead of std::string. Please dont fix my code (I wont learn that way and I will keep bugging you). please just point out the flaws in my logic and suggest a different function/way. platform: gcc version 4.4.1 on Suse Linux 11.2 (2.6.31 kernel) Here's the code main.cpp: // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <cstdlib> /// EXIT_SUCCESS, EXIT_FAILURE #include <iostream> /// cin, cout, ifstream #include <cassert> /// assert // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header for the dictionary class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR CONSTANTS #define ENTER '\n' /// Used to accept new lines, quit program. #define SPACE ' ' /// One way to end the program // /////////////////////////////////////////////////////////////////////////////////// // CUSTOM DATA TYPES /// File Namespace -- keep it local namespace { /// Possible program prompts to display for the user. enum FNS_Prompts { fileName_, /// prints out the name of the file noFile_, /// no file was passed to the program tooMany_, /// more than one file was passed to the program noMemory_, /// Not enough memory to use the program usage_, /// how to use the program word_, /// ask the user to define a word. notFound_, /// the word is not in the dictionary done_, /// the program is closing normally }; } // /////////////////////////////////////////////////////////////////////////////////// // Namespace using namespace std; /// Nothing special in the way of namespaces // /////////////////////////////////////////////////////////////////////////////////// // FUNCTIONS /** prompt() prompts the user to do something, uses enum Prompts for parameter. */ void prompt(FNS_Prompts msg /** determines the prompt to use*/) { switch(msg) { case fileName_ : { cout << ENTER << ENTER << "The file name is: "; break; } case noFile_ : { cout << ENTER << ENTER << "...Sorry, a dictionary file is needed. Try again." << endl; break; } case tooMany_ : { cout << ENTER << ENTER << "...Sorry, you can only specify one dictionary file. Try again." << endl; break; } case noMemory_ : { cout << ENTER << ENTER << "...Sorry, there isn't enough memory available to run this program." << endl; break; } case usage_ : { cout << "USAGE:" << endl << " lookup.exe [dictionary file name]" << endl << endl; break; } case done_ : { cout << ENTER << ENTER << "like Master P says, \"Word.\"" << ENTER << endl; break; } case word_ : { cout << ENTER << ENTER << "Enter a word in the dictionary to get it's definition." << ENTER << "Enter \"?\" to get a sorted list of all words in the dictionary." << ENTER << "... Press the Enter key to quit the program: "; break; } case notFound_ : { cout << ENTER << ENTER << "...Sorry, that word is not in the dictionary." << endl; break; } default : { cout << ENTER << ENTER << "something passed an invalid enum to prompt(). " << endl; assert(false); /// something passed in an invalid enum } } } /** useDictionary() uses the dictionary created by createDictionary * - prompts user to lookup a word * - ends when the user enters an empty word */ void useDictionary(Dictionary &d) { char *userEntry = new char; /// user's input on the command line if( !userEntry ) // check the pointer to the heap { cout << ENTER << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } do { prompt(word_); // test code cout << endl << "----------------------------------------" << endl << "Enter something: "; cin.getline(userEntry, INPUT_LINE_MAX_LEN, ENTER); cout << ENTER << userEntry << endl; }while ( userEntry[0] != NIL && userEntry[0] != SPACE ); // GARBAGE COLLECTION delete[] userEntry; } /** Program Entry * Reads in the required, single file from the command prompt. * - If there is no file, state such and error out. * - If there is more than one file, state such and error out. * - If there is a single file: * - Create the database object * - Populate the database object * - Prompt the user for entry * main() will return EXIT_SUCCESS upon termination. */ int main(int argc, /// the number of files being passed into the program char *argv[] /// pointer to the filename being passed into tthe program ) { // EXECUTE /* Testing code * / char tempFile[INPUT_LINE_MAX_LEN] = {NIL}; cout << "enter filename: "; cin.getline(tempFile, INPUT_LINE_MAX_LEN, '\n'); */ // uncomment after successful debugging if(argc <= 1) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// no file was passed to the program } else if(argc > 2) { prompt(tooMany_); prompt(usage_); return EXIT_FAILURE; /// more than one file was passed to the program } else { prompt(fileName_); cout << argv[1]; // print out name of dictionary file if( !argv[1] ) { prompt(noFile_); prompt(usage_); return EXIT_FAILURE; /// file does not exist } /* file.open( argv[1] ); // open file numEntries >> in.getline(file); // determine number of dictionary objects to create file.close(); // close file Dictionary[ numEntries ](argv[1]); // create the dictionary object */ // TEMPORARY FILE FOR TESTING!!!! //Dictionary scrabble(tempFile); Dictionary scrabble(argv[1]); // creaate the dicitonary object //*/ useDictionary(scrabble); // prompt the user, use the dictionary } // exit return EXIT_SUCCESS; /// terminate program. } Dict.h/.cpp #ifndef DICT_H #define DICT_H // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (Custom header files) #include "entry.h" /// class for dictionary entries // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define INPUT_LINE_MAX_LEN 256 /// Maximum length of each line in the dictionary file class Dictionary { public : // // Do NOT modify the public section of this class // typedef void (*WordDefFunc)(const char *word, const char *definition); Dictionary( const char *filename ); ~Dictionary(); const char *lookupDefinition( const char *word ); void forEach( WordDefFunc func ); private : // // You get to provide the private members // // VARIABLES int m_numEntries; /// stores the number of entries in the dictionary Entry *m_DictEntry_ptr; /// points to an array of class Entry // Private Functions }; #endif ----------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C/C++ Std Library) #include <iostream> /// cout, getline #include <fstream> // ifstream #include <cstring> /// strchr // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "dict.h" /// Header file required by assignment //#include "entry.h" /// Dicitonary Entry Class // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define COMMA ',' /// Delimiter for file #define ENTER '\n' /// Carriage return character #define FILE_ERR_MSG "The data file could not be opened. Program will now terminate." #pragma warning(disable : 4996) /// turn off MS compiler warning about strcpy() // /////////////////////////////////////////////////////////////////////////////////// // Namespace reference using namespace std; // /////////////////////////////////////////////////////////////////////////////////// // PRIVATE MEMBER FUNCTIONS /** * Sorts the dictionary entries. */ /* static void sortDictionary(?) { // sort through the words using qsort } */ /** NO LONGER NEEDED?? * parses out the length of the first cell in a delimited cell * / int getWordLength(char *str /// string of data to parse ) { return strcspn(str, COMMA); } */ // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC MEMBER FUNCTIONS /** constructor for the class * - opens/reads in file * - creates initializes the array of member vars * - creates pointers to entry objects * - stores pointers to entry objects in member var * - ? sort now or later? */ Dictionary::Dictionary( const char *filename ) { // Create a filestream, open the file to be read in ifstream dataFile(filename, ios::in ); /* if( dataFile.fail() ) { cout << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } */ if( dataFile.is_open() ) { // read first line of data // TEST CODE in.getline(dataFile, INPUT_LINE_MAX_LEN) >> m_numEntries; // TEST CODE char temp[INPUT_LINE_MAX_LEN] = {NIL}; // TEST CODE dataFile.getline(temp,INPUT_LINE_MAX_LEN,'\n'); dataFile >> m_numEntries; /** Number of terms in the dictionary file * \todo find out how many lines in the file, subtract one, ingore first line */ //create the array of entries m_DictEntry_ptr = new Entry[m_numEntries]; // check for valid memory allocation if( !m_DictEntry_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // loop thru each line of the file, parsing words/def's and populating entry objects for(int EntryIdx = 0; EntryIdx < m_numEntries; ++EntryIdx) { // VARIABLES char *tempW_ptr; /// points to a temporary word char *tempD_ptr; /// points to a temporary def char *w_ptr; /// points to the word in the Entry object char *d_ptr; /// points to the definition in the Entry int tempWLen; /// length of the temp word string int tempDLen; /// length of the temp def string char tempLine[INPUT_LINE_MAX_LEN] = {NIL}; /// stores a single line from the file // EXECUTE // getline(dataFile, tempLine) // get a "word,def" line from the file dataFile.getline(tempLine, INPUT_LINE_MAX_LEN); // get a "word,def" line from the file // Parse the string tempW_ptr = tempLine; // point the temp word pointer at the first char in the line tempD_ptr = strchr(tempLine, COMMA); // point the def pointer at the comma *tempD_ptr = NIL; // replace the comma with a NIL ++tempD_ptr; // increment the temp def pointer // find the string lengths... +1 to account for terminator tempWLen = strlen(tempW_ptr) + 1; tempDLen = strlen(tempD_ptr) + 1; // Allocate heap memory for the term and defnition w_ptr = new char[ tempWLen ]; d_ptr = new char[ tempDLen ]; // check memory allocation if( !w_ptr && !d_ptr ) { cout << MEM_ERR_MSG << endl; exit(EXIT_FAILURE); } // copy the temp word, def into the newly allocated memory and terminate the strings strcpy(w_ptr,tempW_ptr); w_ptr[tempWLen] = NIL; strcpy(d_ptr,tempD_ptr); d_ptr[tempDLen] = NIL; // set the pointers for the entry objects m_DictEntry_ptr[ EntryIdx ].setWordPtr(w_ptr); m_DictEntry_ptr[ EntryIdx ].setDefPtr(d_ptr); } // close the file dataFile.close(); } else { cout << ENTER << FILE_ERR_MSG << endl; exit(EXIT_FAILURE); } } /** * cleans up dynamic memory */ Dictionary::~Dictionary() { delete[] m_DictEntry_ptr; /// thou shalt not have memory leaks. } /** * Looks up definition */ /* const char *lookupDefinition( const char *word ) { // print out the word ---- definition } */ /** * prints out the entire dictionary in sorted order */ /* void forEach( WordDefFunc func ) { // to sort before or now.... that is the question } */ Entry.h/cpp #ifndef ENTRY_H #define ENTRY_H // /////////////////////////////////////////////////////////////////////////////////// // INCLUDES (C++ Std lib) #include <cstdlib> /// EXIT_SUCCESS, NULL // /////////////////////////////////////////////////////////////////////////////////// // PRE-PROCESSOR MACROS #define NIL '\0' /// C-String terminator #define MEM_ERR_MSG "Memory allocation has failed. Program will now terminate." // /////////////////////////////////////////////////////////////////////////////////// // CLASS DEFINITION class Entry { public: Entry(void) : m_word_ptr(NULL), m_def_ptr(NULL) { /* default constructor */ }; void setWordPtr(char *w_ptr); /// sets the pointer to the word - only if the pointer is empty void setDefPtr(char *d_ptr); /// sets the ponter to the definition - only if the pointer is empty /// returns what is pointed to by the word pointer char getWord(void) const { return *m_word_ptr; } /// returns what is pointed to by the definition pointer char getDef(void) const { return *m_def_ptr; } private: char *m_word_ptr; /** points to a dictionary word */ char *m_def_ptr; /** points to a dictionary definition */ }; #endif -------------------------------------------------- // /////////////////////////////////////////////////////////////////////////////////// // DEPENDENCIES (custom header files) #include "entry.h" /// class header file // /////////////////////////////////////////////////////////////////////////////////// // PUBLIC FUNCTIONS /* * only change the word member var if it is in its initial state */ void Entry::setWordPtr(char *w_ptr) { if(m_word_ptr == NULL) { m_word_ptr = w_ptr; } } /* * only change the def member var if it is in its initial state */ void Entry::setDefPtr(char *d_ptr) { if(m_def_ptr == NULL) { m_word_ptr = d_ptr; } }

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  • C# 5 Async, Part 1: Simplifying Asynchrony – That for which we await

    - by Reed
    Today’s announcement at PDC of the future directions C# is taking excite me greatly.  The new Visual Studio Async CTP is amazing.  Asynchronous code – code which frustrates and demoralizes even the most advanced of developers, is taking a huge leap forward in terms of usability.  This is handled by building on the Task functionality in .NET 4, as well as the addition of two new keywords being added to the C# language: async and await. This core of the new asynchronous functionality is built upon three key features.  First is the Task functionality in .NET 4, and based on Task and Task<TResult>.  While Task was intended to be the primary means of asynchronous programming with .NET 4, the .NET Framework was still based mainly on the Asynchronous Pattern and the Event-based Asynchronous Pattern. The .NET Framework added functionality and guidance for wrapping existing APIs into a Task based API, but the framework itself didn’t really adopt Task or Task<TResult> in any meaningful way.  The CTP shows that, going forward, this is changing. One of the three key new features coming in C# is actually a .NET Framework feature.  Nearly every asynchronous API in the .NET Framework has been wrapped into a new, Task-based method calls.  In the CTP, this is done via as external assembly (AsyncCtpLibrary.dll) which uses Extension Methods to wrap the existing APIs.  However, going forward, this will be handled directly within the Framework.  This will have a unifying effect throughout the .NET Framework.  This is the first building block of the new features for asynchronous programming: Going forward, all asynchronous operations will work via a method that returns Task or Task<TResult> The second key feature is the new async contextual keyword being added to the language.  The async keyword is used to declare an asynchronous function, which is a method that either returns void, a Task, or a Task<T>. Inside the asynchronous function, there must be at least one await expression.  This is a new C# keyword (await) that is used to automatically take a series of statements and break it up to potentially use discontinuous evaluation.  This is done by using await on any expression that evaluates to a Task or Task<T>. For example, suppose we want to download a webpage as a string.  There is a new method added to WebClient: Task<string> WebClient.DownloadStringTaskAsync(Uri).  Since this returns a Task<string> we can use it within an asynchronous function.  Suppose, for example, that we wanted to do something similar to my asynchronous Task example – download a web page asynchronously and check to see if it supports XHTML 1.0, then report this into a TextBox.  This could be done like so: private async void button1_Click(object sender, RoutedEventArgs e) { string url = "http://reedcopsey.com"; string content = await new WebClient().DownloadStringTaskAsync(url); this.textBox1.Text = string.Format("Page {0} supports XHTML 1.0: {1}", url, content.Contains("XHTML 1.0")); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Let’s walk through what’s happening here, step by step.  By adding the async contextual keyword to the method definition, we are able to use the await keyword on our WebClient.DownloadStringTaskAsync method call. When the user clicks this button, the new method (Task<string> WebClient.DownloadStringTaskAsync(string)) is called, which returns a Task<string>.  By adding the await keyword, the runtime will call this method that returns Task<string>, and execution will return to the caller at this point.  This means that our UI is not blocked while the webpage is downloaded.  Instead, the UI thread will “await” at this point, and let the WebClient do it’s thing asynchronously. When the WebClient finishes downloading the string, the user interface’s synchronization context will automatically be used to “pick up” where it left off, and the Task<string> returned from DownloadStringTaskAsync is automatically unwrapped and set into the content variable.  At this point, we can use that and set our text box content. There are a couple of key points here: Asynchronous functions are declared with the async keyword, and contain one or more await expressions In addition to the obvious benefits of shorter, simpler code – there are some subtle but tremendous benefits in this approach.  When the execution of this asynchronous function continues after the first await statement, the initial synchronization context is used to continue the execution of this function.  That means that we don’t have to explicitly marshal the call that sets textbox1.Text back to the UI thread – it’s handled automatically by the language and framework!  Exception handling around asynchronous method calls also just works. I’d recommend every C# developer take a look at the documentation on the new Asynchronous Programming for C# and Visual Basic page, download the Visual Studio Async CTP, and try it out.

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  • Parallelism in .NET – Part 13, Introducing the Task class

    - by Reed
    Once we’ve used a task-based decomposition to decompose a problem, we need a clean abstraction usable to implement the resulting decomposition.  Given that task decomposition is founded upon defining discrete tasks, .NET 4 has introduced a new API for dealing with task related issues, the aptly named Task class. The Task class is a wrapper for a delegate representing a single, discrete task within your decomposition.  We will go into various methods of construction for tasks later, but, when reduced to its fundamentals, an instance of a Task is nothing more than a wrapper around a delegate with some utility functionality added.  In order to fully understand the Task class within the new Task Parallel Library, it is important to realize that a task really is just a delegate – nothing more.  In particular, note that I never mentioned threading or parallelism in my description of a Task.  Although the Task class exists in the new System.Threading.Tasks namespace: Tasks are not directly related to threads or multithreading. Of course, Task instances will typically be used in our implementation of concurrency within an application, but the Task class itself does not provide the concurrency used.  The Task API supports using Tasks in an entirely single threaded, synchronous manner. Tasks are very much like standard delegates.  You can execute a task synchronously via Task.RunSynchronously(), or you can use Task.Start() to schedule a task to run, typically asynchronously.  This is very similar to using delegate.Invoke to execute a delegate synchronously, or using delegate.BeginInvoke to execute it asynchronously. The Task class adds some nice functionality on top of a standard delegate which improves usability in both synchronous and multithreaded environments. The first addition provided by Task is a means of handling cancellation via the new unified cancellation mechanism of .NET 4.  If the wrapped delegate within a Task raises an OperationCanceledException during it’s operation, which is typically generated via calling ThrowIfCancellationRequested on a CancellationToken, or if the CancellationToken used to construct a Task instance is flagged as canceled, the Task’s IsCanceled property will be set to true automatically.  This provides a clean way to determine whether a Task has been canceled, often without requiring specific exception handling. Tasks also provide a clean API which can be used for waiting on a task.  Although the Task class explicitly implements IAsyncResult, Tasks provide a nicer usage model than the traditional .NET Asynchronous Programming Model.  Instead of needing to track an IAsyncResult handle, you can just directly call Task.Wait() to block until a Task has completed.  Overloads exist for providing a timeout, a CancellationToken, or both to prevent waiting indefinitely.  In addition, the Task class provides static methods for waiting on multiple tasks – Task.WaitAll and Task.WaitAny, again with overloads providing time out options.  This provides a very simple, clean API for waiting on single or multiple tasks. Finally, Tasks provide a much nicer model for Exception handling.  If the delegate wrapped within a Task raises an exception, the exception will automatically get wrapped into an AggregateException and exposed via the Task.Exception property.  This exception is stored with the Task directly, and does not tear down the application.  Later, when Task.Wait() (or Task.WaitAll or Task.WaitAny) is called on this task, an AggregateException will be raised at that point if any of the tasks raised an exception.  For example, suppose we have the following code: Task taskOne = new Task( () => { throw new ApplicationException("Random Exception!"); }); Task taskTwo = new Task( () => { throw new ArgumentException("Different exception here"); }); // Start the tasks taskOne.Start(); taskTwo.Start(); try { Task.WaitAll(new[] { taskOne, taskTwo }); } catch (AggregateException e) { Console.WriteLine(e.InnerExceptions.Count); foreach (var inner in e.InnerExceptions) Console.WriteLine(inner.Message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, our routine will print: 2 Different exception here Random Exception! Note that we had two separate tasks, each of which raised two distinctly different types of exceptions.  We can handle this cleanly, with very little code, in a much nicer manner than the Asynchronous Programming API.  We no longer need to handle TargetInvocationException or worry about implementing the Event-based Asynchronous Pattern properly by setting the AsyncCompletedEventArgs.Error property.  Instead, we just raise our exception as normal, and handle AggregateException in a single location in our calling code.

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  • Parallelism in .NET – Part 16, Creating Tasks via a TaskFactory

    - by Reed
    The Task class in the Task Parallel Library supplies a large set of features.  However, when creating the task, and assigning it to a TaskScheduler, and starting the Task, there are quite a few steps involved.  This gets even more cumbersome when multiple tasks are involved.  Each task must be constructed, duplicating any options required, then started individually, potentially on a specific scheduler.  At first glance, this makes the new Task class seem like more work than ThreadPool.QueueUserWorkItem in .NET 3.5. In order to simplify this process, and make Tasks simple to use in simple cases, without sacrificing their power and flexibility, the Task Parallel Library added a new class: TaskFactory. The TaskFactory class is intended to “Provide support for creating and scheduling Task objects.”  Its entire purpose is to simplify development when working with Task instances.  The Task class provides access to the default TaskFactory via the Task.Factory static property.  By default, TaskFactory uses the default TaskScheduler to schedule tasks on a ThreadPool thread.  By using Task.Factory, we can automatically create and start a task in a single “fire and forget” manner, similar to how we did with ThreadPool.QueueUserWorkItem: Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This provides us with the same level of simplicity we had with ThreadPool.QueueUserWorkItem, but even more power.  For example, we can now easily wait on the task: // Start our task on a background thread var task = Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); // Do other work on the main thread, // while the task above executes in the background this.ExecuteWorkSynchronously(); // Wait for the background task to finish task.Wait(); TaskFactory simplifies creation and startup of simple background tasks dramatically. In addition to using the default TaskFactory, it’s often useful to construct a custom TaskFactory.  The TaskFactory class includes an entire set of constructors which allow you to specify the default configuration for every Task instance created by that factory.  This is particularly useful when using a custom TaskScheduler.  For example, look at the sample code for starting a task on the UI thread in Part 15: // Given the following, constructed on the UI thread // TaskScheduler uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // When inside a background task, we can do string status = GetUpdatedStatus(); (new Task(() => { statusLabel.Text = status; })) .Start(uiScheduler); This is actually quite a bit more complicated than necessary.  When we create the uiScheduler instance, we can use that to construct a TaskFactory that will automatically schedule tasks on the UI thread.  To do that, we’d create the following on our main thread, prior to constructing our background tasks: // Construct a task scheduler from the current SynchronizationContext (UI thread) var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // Construct a new TaskFactory using our UI scheduler var uiTaskFactory = new TaskFactory(uiScheduler); If we do this, when we’re on a background thread, we can use this new TaskFactory to marshal a Task back onto the UI thread.  Our previous code simplifies to: // When inside a background task, we can do string status = GetUpdatedStatus(); // Update our UI uiTaskFactory.StartNew( () => statusLabel.Text = status); Notice how much simpler this becomes!  By taking advantage of the convenience provided by a custom TaskFactory, we can now marshal to set data on the UI thread in a single, clear line of code!

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  • Tweaking a few URL validation settings on ASP.NET v4.0

    - by Carlyle Dacosta
    ASP.NET has a few default settings for URLs out of the box. These can be configured quite easily in the web.config file within the  <system.web>/<httpRuntime> configuration section. Some of these are: <httpRuntime maxUrlLength=”<number here>”. This number should be an integer value (defaults to 260 characters). The value must be greater than or equal to zero, though obviously small values will lead to an un-useable website. This attribute gates the length of the Url without query string. <httpRuntime maxQueryStringLength=”<number here>”. This number should be an integer value (defaults to 2048 characters). The value must be greater than or equal to zero, though obviously small values will lead to an un-useable website. <httpRuntime requestPathInvalidCharacters=”List of characters you need included in ASP.NETs validation checks”. By default the characters are “<,>,*,%,&,:,\,?”. However once can easily change this by setting by modifying web.config. Remember, these characters can be specified in a variety of formats. For example, I want the character ‘!’ to be included in ASP.NETs URL validation logic. So I set the following: <httpRuntime requestPathInvalidCharacters=”<,>,*,%,&,:,\,?,!”. A character could also be specified in its xml encoded form. ‘&lt;;’ would mean the ‘<’ sign). I could specify the ‘!’ in its xml encoded unicode format such as requestPathInvalidCharacters=”<,>,*,%,&,:,\,?,$#x0021;” or I could specify it in its unicode encoded form or in the “<,>,*,%,&,:,\,?,%u0021” format. The following settings can be applied at Root Web.Config level, App Web.config level, Folder level or within a location tag: <location path="some path here"> <system.web> <httpRuntime maxUrlLength="" maxQueryStringLength="" requestPathInvalidChars="" .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If any of the above settings fail request validation, an Http 400 “Bad Request” HttpException is thrown. These can be easily handled on the Application_Error handler on Global.asax.   Also, a new attribute in <httpRuntime /> called “relaxedUrlToFileSystemMapping” has been added with a default of false. <httpRuntime … relaxedUrlToFileSystemMapping="true|false" /> When the relaxedUrlToFileSystemMapping attribute is set to false inbound Urls still need to be valid NTFS file paths. For example Urls (sans query string) need to be less than 260 characters; no path segment within a Url can use old-style DOS device names (LPT1, COM1, etc…); Urls must be valid Windows file paths. A url like “http://digg.com/http://cnn.com” should work with this attribute set to true (of course a few characters will need to be unblocked by removing them from requestPathInvalidCharacters="" above). Managed configuration for non-NTFS-compliant Urls is determined from the first valid configuration path found when walking up the path segments of the Url. For example, if the request Url is "/foo/bar/baz/<blah>data</blah>", and there is a web.config in the "/foo/bar" directory, then the managed configuration for the request comes from merging the configuration hierarchy to include the web.config from "/foo/bar". The value of the public property HttpRequest.PhysicalPath is set to [physical file path of the application root] + "REQUEST_URL_IS_NOT_A_VALID_FILESYSTEM_PATH". For example, given a request Url like "/foo/bar/baz/<blah>data</blah>", where the application root is "/foo/bar" and the physical file path for that root is "c:\inetpub\wwwroot\foo\bar", then PhysicalPath would be "c:\inetpub\wwwroot\foo\bar\ REQUEST_URL_IS_NOT_A_VALID_FILESYSTEM_PATH". Carl Dacosta ASP.NET QA Team

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  • Tweaking a few URL validation settings on ASP.NET v4.0

    - by Carlyle Dacosta
    ASP.NET has a few default settings for URLs out of the box. These can be configured quite easily in the web.config file within the  <system.web>/<httpRuntime> configuration section. Some of these are: <httpRuntime maxUrlLength=”<number here>” This number should be an integer value (defaults to 260 characters). The value must be greater than or equal to zero, though obviously small values will lead to an un-useable website. This attribute gates the length of the Url without query string. <httpRuntime maxQueryStringLength=”<number here>”. This number should be an integer value (defaults to 2048 characters). The value must be greater than or equal to zero, though obviously small values will lead to an un-useable website. <httpRuntime requestPathInvalidCharacters=”List of characters you need included in ASP.NETs validation checks” /> By default the characters are “<,>,*,%,&,:,\,?”. However once can easily change this by setting by modifying web.config. Remember, these characters can be specified in a variety of formats. For example, I want the character ‘!’ to be included in ASP.NETs URL validation logic. So I set the following: <httpRuntime requestPathInvalidCharacters=”<,>,*,%,&,:,\,?,!”. A character could also be specified in its xml encoded form. ‘&lt;;’ would mean the ‘<’ sign). I could specify the ‘!’ in its xml encoded unicode format such as requestPathInvalidCharacters=”<,>,*,%,&,:,\,?,$#x0021;” or I could specify it in its unicode encoded form or in the “<,>,*,%,&,:,\,?,%u0021” format. The following settings can be applied at Root Web.Config level, App Web.config level, Folder level or within a location tag: <location path="some path here"> <system.web> <httpRuntime maxUrlLength="" maxQueryStringLength="" requestPathInvalidChars="" /> .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If any of the above settings fail request validation, an Http 400 “Bad Request” HttpException is thrown. These can be easily handled on the Application_Error handler on Global.asax.   Also, a new attribute in <httpRuntime /> called “relaxedUrlToFileSystemMapping” has been added with a default of false. <httpRuntime … relaxedUrlToFileSystemMapping="true|false" /> When the relaxedUrlToFileSystemMapping attribute is set to false inbound Urls still need to be valid NTFS file paths. For example Urls (sans query string) need to be less than 260 characters; no path segment within a Url can use old-style DOS device names (LPT1, COM1, etc…); Urls must be valid Windows file paths. A url like “http://digg.com/http://cnn.com” should work with this attribute set to true (of course a few characters will need to be unblocked by removing them from requestPathInvalidCharacters="" above). Managed configuration for non-NTFS-compliant Urls is determined from the first valid configuration path found when walking up the path segments of the Url. For example, if the request Url is "/foo/bar/baz/<blah>data</blah>", and there is a web.config in the "/foo/bar" directory, then the managed configuration for the request comes from merging the configuration hierarchy to include the web.config from "/foo/bar". The value of the public property HttpRequest.PhysicalPath is set to [physical file path of the application root] + "REQUEST_URL_IS_NOT_A_VALID_FILESYSTEM_PATH". For example, given a request Url like "/foo/bar/baz/<blah>data</blah>", where the application root is "/foo/bar" and the physical file path for that root is "c:\inetpub\wwwroot\foo\bar", then PhysicalPath would be "c:\inetpub\wwwroot\foo\bar\ REQUEST_URL_IS_NOT_A_VALID_FILESYSTEM_PATH".

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  • Parallelism in .NET – Part 8, PLINQ’s ForAll Method

    - by Reed
    Parallel LINQ extends LINQ to Objects, and is typically very similar.  However, as I previously discussed, there are some differences.  Although the standard way to handle simple Data Parellelism is via Parallel.ForEach, it’s possible to do the same thing via PLINQ. PLINQ adds a new method unavailable in standard LINQ which provides new functionality… LINQ is designed to provide a much simpler way of handling querying, including filtering, ordering, grouping, and many other benefits.  Reading the description in LINQ to Objects on MSDN, it becomes clear that the thinking behind LINQ deals with retrieval of data.  LINQ works by adding a functional programming style on top of .NET, allowing us to express filters in terms of predicate functions, for example. PLINQ is, generally, very similar.  Typically, when using PLINQ, we write declarative statements to filter a dataset or perform an aggregation.  However, PLINQ adds one new method, which provides a very different purpose: ForAll. The ForAll method is defined on ParallelEnumerable, and will work upon any ParallelQuery<T>.  Unlike the sequence operators in LINQ and PLINQ, ForAll is intended to cause side effects.  It does not filter a collection, but rather invokes an action on each element of the collection. At first glance, this seems like a bad idea.  For example, Eric Lippert clearly explained two philosophical objections to providing an IEnumerable<T>.ForEach extension method, one of which still applies when parallelized.  The sole purpose of this method is to cause side effects, and as such, I agree that the ForAll method “violates the functional programming principles that all the other sequence operators are based upon”, in exactly the same manner an IEnumerable<T>.ForEach extension method would violate these principles.  Eric Lippert’s second reason for disliking a ForEach extension method does not necessarily apply to ForAll – replacing ForAll with a call to Parallel.ForEach has the same closure semantics, so there is no loss there. Although ForAll may have philosophical issues, there is a pragmatic reason to include this method.  Without ForAll, we would take a fairly serious performance hit in many situations.  Often, we need to perform some filtering or grouping, then perform an action using the results of our filter.  Using a standard foreach statement to perform our action would avoid this philosophical issue: // Filter our collection var filteredItems = collection.AsParallel().Where( i => i.SomePredicate() ); // Now perform an action foreach (var item in filteredItems) { // These will now run serially item.DoSomething(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This would cause a loss in performance, since we lose any parallelism in place, and cause all of our actions to be run serially. We could easily use a Parallel.ForEach instead, which adds parallelism to the actions: // Filter our collection var filteredItems = collection.AsParallel().Where( i => i.SomePredicate() ); // Now perform an action once the filter completes Parallel.ForEach(filteredItems, item => { // These will now run in parallel item.DoSomething(); }); This is a noticeable improvement, since both our filtering and our actions run parallelized.  However, there is still a large bottleneck in place here.  The problem lies with my comment “perform an action once the filter completes”.  Here, we’re parallelizing the filter, then collecting all of the results, blocking until the filter completes.  Once the filtering of every element is completed, we then repartition the results of the filter, reschedule into multiple threads, and perform the action on each element.  By moving this into two separate statements, we potentially double our parallelization overhead, since we’re forcing the work to be partitioned and scheduled twice as many times. This is where the pragmatism comes into play.  By violating our functional principles, we gain the ability to avoid the overhead and cost of rescheduling the work: // Perform an action on the results of our filter collection .AsParallel() .Where( i => i.SomePredicate() ) .ForAll( i => i.DoSomething() ); The ability to avoid the scheduling overhead is a compelling reason to use ForAll.  This really goes back to one of the key points I discussed in data parallelism: Partition your problem in a way to place the most work possible into each task.  Here, this means leaving the statement attached to the expression, even though it causes side effects and is not standard usage for LINQ. This leads to my one guideline for using ForAll: The ForAll extension method should only be used to process the results of a parallel query, as returned by a PLINQ expression. Any other usage scenario should use Parallel.ForEach, instead.

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  • Parallelism in .NET – Part 17, Think Continuations, not Callbacks

    - by Reed
    In traditional asynchronous programming, we’d often use a callback to handle notification of a background task’s completion.  The Task class in the Task Parallel Library introduces a cleaner alternative to the traditional callback: continuation tasks. Asynchronous programming methods typically required callback functions.  For example, MSDN’s Asynchronous Delegates Programming Sample shows a class that factorizes a number.  The original method in the example has the following signature: public static bool Factorize(int number, ref int primefactor1, ref int primefactor2) { //... .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } However, calling this is quite “tricky”, even if we modernize the sample to use lambda expressions via C# 3.0.  Normally, we could call this method like so: int primeFactor1 = 0; int primeFactor2 = 0; bool answer = Factorize(10298312, ref primeFactor1, ref primeFactor2); Console.WriteLine("{0}/{1} [Succeeded {2}]", primeFactor1, primeFactor2, answer); If we want to make this operation run in the background, and report to the console via a callback, things get tricker.  First, we need a delegate definition: public delegate bool AsyncFactorCaller( int number, ref int primefactor1, ref int primefactor2); Then we need to use BeginInvoke to run this method asynchronously: int primeFactor1 = 0; int primeFactor2 = 0; AsyncFactorCaller caller = new AsyncFactorCaller(Factorize); caller.BeginInvoke(10298312, ref primeFactor1, ref primeFactor2, result => { int factor1 = 0; int factor2 = 0; bool answer = caller.EndInvoke(ref factor1, ref factor2, result); Console.WriteLine("{0}/{1} [Succeeded {2}]", factor1, factor2, answer); }, null); This works, but is quite difficult to understand from a conceptual standpoint.  To combat this, the framework added the Event-based Asynchronous Pattern, but it isn’t much easier to understand or author. Using .NET 4’s new Task<T> class and a continuation, we can dramatically simplify the implementation of the above code, as well as make it much more understandable.  We do this via the Task.ContinueWith method.  This method will schedule a new Task upon completion of the original task, and provide the original Task (including its Result if it’s a Task<T>) as an argument.  Using Task, we can eliminate the delegate, and rewrite this code like so: var background = Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }); background.ContinueWith(task => Console.WriteLine("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result)); This is much simpler to understand, in my opinion.  Here, we’re explicitly asking to start a new task, then continue the task with a resulting task.  In our case, our method used ref parameters (this was from the MSDN Sample), so there is a little bit of extra boiler plate involved, but the code is at least easy to understand. That being said, this isn’t dramatically shorter when compared with our C# 3 port of the MSDN code above.  However, if we were to extend our requirements a bit, we can start to see more advantages to the Task based approach.  For example, supposed we need to report the results in a user interface control instead of reporting it to the Console.  This would be a common operation, but now, we have to think about marshaling our calls back to the user interface.  This is probably going to require calling Control.Invoke or Dispatcher.Invoke within our callback, forcing us to specify a delegate within the delegate.  The maintainability and ease of understanding drops.  However, just as a standard Task can be created with a TaskScheduler that uses the UI synchronization context, so too can we continue a task with a specific context.  There are Task.ContinueWith method overloads which allow you to provide a TaskScheduler.  This means you can schedule the continuation to run on the UI thread, by simply doing: Task.Factory.StartNew( () => { int primeFactor1 = 0; int primeFactor2 = 0; bool result = Factorize(10298312, ref primeFactor1, ref primeFactor2); return new { Result = result, Factor1 = primeFactor1, Factor2 = primeFactor2 }; }).ContinueWith(task => textBox1.Text = string.Format("{0}/{1} [Succeeded {2}]", task.Result.Factor1, task.Result.Factor2, task.Result.Result), TaskScheduler.FromCurrentSynchronizationContext()); This is far more understandable than the alternative.  By using Task.ContinueWith in conjunction with TaskScheduler.FromCurrentSynchronizationContext(), we get a simple way to push any work onto a background thread, and update the user interface on the proper UI thread.  This technique works with Windows Presentation Foundation as well as Windows Forms, with no change in methodology.

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