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  • MySQL: Get only count of result set.

    - by Varun
    I am using MVC with PHP/MySQL. Suppose I am using 10 functions with different queries for fetching details from the database. But at other times I may want to get only the count of the result that will be returned by the query. What is the standard way to handle such situation. Should I write 10 more functions which duplicate almost whole query and return only the count. Or Should I always return the count also with the result set Or I can pass a flag to indicate that the function should return count only, and then based on the flag I will dynamically generate the (select part of) query. Or Is there a better way?

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  • Template function as a template argument

    - by Kos
    I've just got confused how to implement something in a generic way in C++. It's a bit convoluted, so let me explain step by step. Consider such code: void a(int) { // do something } void b(int) { // something else } void function1() { a(123); a(456); } void function2() { b(123); b(456); } void test() { function1(); function2(); } It's easily noticable that function1 and function2 do the same, with the only different part being the internal function. Therefore, I want to make function generic to avoid code redundancy. I can do it using function pointers or templates. Let me choose the latter for now. My thinking is that it's better since the compiler will surely be able to inline the functions - am I correct? Can compilers still inline the calls if they are made via function pointers? This is a side-question. OK, back to the original point... A solution with templates: void a(int) { // do something } void b(int) { // something else } template<void (*param)(int) > void function() { param(123); param(456); } void test() { function<a>(); function<b>(); } All OK. But I'm running into a problem: Can I still do that if a and b are generics themselves? template<typename T> void a(T t) { // do something } template<typename T> void b(T t) { // something else } template< ...param... > // ??? void function() { param<SomeType>(someobj); param<AnotherType>(someotherobj); } void test() { function<a>(); function<b>(); } I know that a template parameter can be one of: a type, a template type, a value of a type. None of those seems to cover my situation. My main question is hence: How do I solve that, i.e. define function() in the last example? (Yes, function pointers seem to be a workaround in this exact case - provided they can also be inlined - but I'm looking for a general solution for this class of problems).

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  • What is the fastest way to do division in C for 8bit MCUs?

    - by Jordan S
    I am working on the firmware for a device that uses an 8bit mcu (8051 architecture). I am using SDCC (Small Device C Compiler). I have a function that I use to set the speed of a stepper motor that my circuit is driving. The speed is set by loading a desired value into the reload register for a timer. I have a variable, MotorSpeed that is in the range of 0 to 1200 which represents pulses per second to the motor. My function to convert MotorSpeed to the correct 16bit reload value is shown below. I know that float point operations are pretty slow and I am wondering if there is a faster way of doing this... void SetSpeed() { float t = MotorSpeed; unsigned int j = 0; t = 1/t ; t = t / 0.000001; j = MaxInt - t; TMR3RL = j; // Set reload register for desired freq return; }

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  • what to do with a flawed C++ skills test

    - by Mike Landis
    In the following gcc.gnu.org post, Nathan Myers says that a C++ skills test at SANS Consulting Services contained three errors in nine questions: Looking around, one of fthe first on-line C++ skills tests I ran across was: http://www.geekinterview.com/question_details/13090 I looked at question 1... find(int x,int y) { return ((x<y)?0:(x-y)):} call find(a,find(a,b)) use to find (a) maximum of a,b (b) minimum of a,b (c) positive difference of a,b (d) sum of a,b ... immediately wondering why would anyone write anything so obtuse. Getting past the absurdity, I didn't really like any of the answers, immediately eliminating (a) and (b) because you can get back zero (which is neither a nor b) in a variety of circumstances. Sum or difference seemed more likely, except that you could also get zero regardless of the magnitudes of a and b. So... I put Matlab to work (code below) and found: when either a or b is negative you get zero; when b a you get a; otherwise you get b, so the answer is (b) min(a,b), if a and b are positive, though strictly speaking the answer should be none of the above because there are no range restrictions on either variable. That forces test takers into a dilemma - choose the best available answer and be wrong in 3 of 4 quadrants, or don't answer, leaving the door open to the conclusion that the grader thinks you couldn't figure it out. The solution for test givers is to fix the test, but in the interim, what's the right course of action for test takers? Complain about the questions? function z = findfunc(x,y) for i=1:length(x) if x(i) < y(i) z(i) = 0; else z(i) = x(i) - y(i); end end end function [b,d1,z] = plotstuff() k = 50; a = [-k:1:k]; b = (2*k+1) * rand(length(a),1) - k; d1 = findfunc(a,b); z = findfunc(a,d1); plot( a, b, 'r.', a, d1, 'g-', a, z, 'b-'); end

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  • socket timeout and remove O_NONBLOCK option

    - by juxstapose
    Hello, I implemented a socket timeout and retry but in order to do it I had to set the socket as a non-blocking socket. However, I need the socket to block. This was my attempt at a solution to these two problems. This is not working. Subsequent send calls block but never send any data. When I connect without the select and the timeout, subsequent send calls work normally. References: C: socket connection timeout How to reset a socket back to blocking mode (after I set it to nonblocking mode)? Code: fd_set fdset; struct timeval tv; fcntl(dsock, F_SETFL, O_NONBLOCK); tv.tv_sec = theDeviceTimeout; tv.tv_usec = 0; int retries=0; logi(theLogOutput, LOG_INFO, "connecting to device socket num retrys: %i", theDeviceRetry); for(retries=0;retries<theDeviceRetry;retries++) { connect(dsock, (struct sockaddr *)&daddr, sizeof daddr); FD_ZERO(&fdset); FD_SET(dsock, &fdset); if (select(dsock + 1, NULL, &fdset, NULL, &tv) == 1) { int so_error; socklen_t slen = sizeof so_error; getsockopt(dsock, SOL_SOCKET, SO_ERROR, &so_error, &slen); if (so_error == 0) { logi(theLogOutput, LOG_INFO, "connected to socket on port %i on %s", theDevicePort, theDeviceIP); break; } else { logi(theLogOutput, LOG_WARN, "connect to %i failed on ip %s because %s retries %i", theDevicePort, theDeviceIP, strerror(errno), retries); logi(theLogOutput, LOG_WARN, "failed to connect to device %s", strerror(errno)); logi(theLogOutput, LOG_WARN, "error: %i %s", so_error, strerror(so_error)); continue; } } } int opts; opts = fcntl(dsock,F_GETFL); logi(theLogOutput, LOG_DEBUG, "clearing nonblock option %i retries %i", opts, retries); opts ^= O_NONBLOCK; fcntl(dsock, F_SETFL, opts);

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  • Property value of a String object in JavaScript

    - by naivists
    As far as I understand, every string is an object in Javascript. Still, it "does not work" as I expect it to be: var a="abc"; //here we get a new string object a.b = 123; //I seem to declare a property "b" of that object alert(a.b); //alerts "undefined" However, if I try to define a string in the "wrong way", everything works as expected var a=new String("abc"); // a.b = 123; alert(a.b); //alerts "123" Why is that so?

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  • Do you like languages that let you put the "then" before the "if"?

    - by Matt Hamilton
    I was reading through some C# code of mine today and found this line: if (ProgenyList.ItemContainerGenerator.Status != System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated) return; Notice that you can tell without scrolling that it's an "if" statement that works with ItemContainerGenerator.Status, but you can't easily tell that if the "if" clause evaluates to "false" the method will return at that point. Realistically I should have moved the "return" statement to a line by itself, but it got me thinking about languages that allow the "then" part of the statement first. If C# permitted it, the line could look like this: return if (ProgenyList.ItemContainerGenerator.Status != System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated); This might be a bit "argumentative", but I'm wondering what people think about this kind of construct. It might serve to make lines like the one above more readable, but it also might be disastrous. Imagine this code: return 3 if (x > y); Logically we can only return if x y, because there's no "else", but part of me looks at that and thinks, "are we still returning if x <= y? If so, what are we returning?" What do you think of the "then before the if" construct? Does it exist in your language of choice? Do you use it often? Would C# benefit from it?

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  • What language is this???

    - by Misha Koshelev
    Dear All: I thought this was Javascript... but parser is giving me trouble. Any ideas? Thank you! Misha for (;;); {"error":0,"errorSummary":"","errorDescription":"","errorIsWarning":false,"silentError":0,"payload":{"collections": [{"name":"bcm","type":"flp","filter":"flp_662923563701","value":"662923563701","editable":true,"deletable":true,"members": ["1319651388","539562714","710814793","569071038","1553739575","2413243"]}, {"name":"mstp","type":"flp","filter":"flp_715806870131","value":"715806870131","editable":true,"deletable":true,"members": ["1263807225","1159429816","508447486","508005223","1234906348","642723993","552875889","23401888","10701320","8302901","7931988","3007490","1286522890","1128447272","1076062553","775679867","737520202","640799498","224400055","224400048","14211567","7909445","3005965","2404364","218216","660037273","224400089","73306230","9603033","1111694","1034418884","775680513" ,"704526828","518753881","512477182","224400016","24904610","19000876","5403952","3005641","2100348","100000421128298","1445411167","691445174","1020020100","795471177","683724539","682441089","532450522","224400129","224400005","3006522","2246813","1302265","7197","1900494", "100000474978266","2533582","1205125","1384091677","1260996959","710814793","514951289","224400164","224400156","173601800","13304723","7938844","3004783","3001379","302817","716739950 ","706849","1418109424","562676898","82501644","3007569","13173"]}, {"name":"mystery","type":"flp","filter":"flp_687949656211","value":"687949656211","editable":true,"deletable":true,"members": ["100001286464748","508123007","100001161894460","1148567030","1048974191","769992391","831734347","15347","1297180076","756692945","3005266","733396195","34410910","100000940154241"," 748426280","569417581","1318922027","100000164920046","1475269609","1436536592","10000016210 8385","754095305","100000421128298","537833189","100000692471928","7920231","673753496","3006217","1221878","8365333","1128447272","224400133","218216","505457123","1421958541","183829 5926","2349408","1622810085","1201640391","510959992","23429895","542118016","1017385668","586225579","625100539","100000474886633","26404148","1384091677","224400156","806908635","843 187401","400435","768261176","7901808","748496482","1541469473","2511982","25401573","503715 506","1226000844","559195162","41400094","1099436201","409816","1584400985","1577092523","100000349351880","199301581"]},{"name":"SMS Subscriptions","type":"ms","filter":"ms","value":"3","editable":true,"deletable":false,"members":[]}],"current_view":false}}

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  • scheme2lisp::define function and pass it as parameter

    - by Stas
    Hi! Im need translate some code from scheme to common lisp. Now I have something like this (defun sum (term a next b) (if (> a b) 0 (+ (term a) (sum term (next a) b)))) (defun sum-int (a b) (defun (ident x) x ) (sum ident a 1+ b)) But it doesn't interprete with out errors. * - DEFUN: the name of a function must be a symbol, not (IDENT X) Help me plese. Thanks

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  • how does Cocoa compare to Microsoft, Qt?

    - by Paperflyer
    I have done a few months of development with Qt (built GUI programatically only) and am now starting to work with Cocoa. I have to say, I love Cocoa. A lot of the things that seemed hard in Qt are easy with Cocoa. Obj-C seems to be far less complex than C++. This is probably just me, so: Ho do you feel about this? How does Cocoa compare to WPF (is that the right framework?) to Qt? How does Obj-C compare to C# to C++? How does XCode/Interface Builder compare to Visual Studio to Qt Creator? How do the Documentations compare? For example, I find Cocoa's Outlets/Actions far more useful than Qt's Signals and Slots because they actually seem to cover most GUI interactions while I had to work around Signals/Slots half the time. (Did I just use them wrong?) Also, the standard templates of XCode give me copy/paste, undo/redo, save/open and a lot of other stuff practically for free while these were rather complex tasks in Qt. Please only answer if you have actual knowledge of at least two of these development environments/frameworks/languages.

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  • Where to draw the line between efficiency and practicality

    - by dclowd9901
    I understand very well the need for websites' front ends to be coded and compressed as much as possible, however, I feel like I have more lax standards than others when it comes to practical applications. For instance, while I understand why some would, I don't see anything wrong with putting selectors in the <html> or <body> tags on a website with an expected small visitation rate. I would only do this for a cheap website for a small client, because I can't really justify the cost of time otherwise. So, that said, do you think it's okay to draw a line? Where do you draw yours?

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  • read angles in radian and convert them in degrees/minutes/seconds

    - by Amadou
    n=0; disp('This program performs an angle conversion'); disp('input data set to a straight line. Enter the name'); disp('of the file containing the input Lambda in radian: '); filename = input(' ','s'); [fid,msg] = fopen(filename,'rt'); if fid < 0 disp(msg); else A=textscan(fid, '%g',1); while ~feof(fid) Lambda = A(1); n = n + 1; A = textscan(fid, '%f',1); end fclose(fid); end Alpha=Lambda*180/pi; fprintf('Angle converted from radian to degree/minutes/seconds:\n'); fprintf('Alpha =%12d\n',Alpha); fprintf('No of angles =%12d\n',n);

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  • Why isn't LISP more widely used?

    - by Chris
    I've heard a lot of people espouse the capabilities of LISP and its omnipotent macros. If LISP is such a great language, why isn't it being adopted more? What problems is LISP facing that is holding it back from (re)emerging as popular language? Is it something about LISP itself ("those brackets!" isn't the answer, is it?!), or its competitors (e.g. the dominance of Java, .NET)?

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  • Correct usage of socket_select().

    - by Mark Tomlin
    What is the correct way to use socket_select within PHP to send and receive data? I have a connection to the server that allows for both TCP & UDP packet connections, I am utilizing both. Within these connections I'm both sending and receiving packets on the same port, but the TCP packet will be sent on one port (29999) and UDP will be sent on another port (30000). The transmission type will be that of AF_INET. The IP address will be loopback 127.0.0.1. I have many questions on how to create a socket connection within this scenario. For example, is it better to use socket_create_pair to make the connection, or use just socket_create followed by socket_connect, and then implement socket_select? There is a chance that no data will be sent from the server to the client, and it is up to the client to maintain the connection. This will be done by utilizing the time out function within the socket_select call. Should no data be sent within the time limit, the socket_select function will break and a keep alive packet can then be sent. The following script is of the client. // Create $TCP = socket_create(AF_INET, SOCK_STREAM, SOL_TCP); $UDP = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP); // Misc $isAlive = TRUE; $UDPPort = 30000; define('ISP_ISI', 1); // Connect socket_connect($TCP, '127.0.0.1', 29999); socket_connect($UDP, '127.0.0.1', $UDPPort); // Construct Parameters $recv = array($TCP, $UDP); $null = NULL; // Make The Packet to Send. $packet = pack('CCCxSSxCSa16a16', 44, ISP_ISI, 1, $UDPPort, 0, '!', 0, 'AdminPass', 'SocketSelect'); // Send ISI (InSim Init) Packet socket_write($TCP, $packet); /* Main Program Loop */ while ($isAlive == TRUE) { // Socket Select $sock = socket_select($recv, $null, $null, 5); // Check Status if ($sock === FALSE) $isAlive = FALSE; # Error else if ($sock > 0) # How does one check to find what socket changed? else # Something else happed, don't know what as it's not in the documentation, Could this be our timeout getting tripped? }

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  • Where is the money?

    - by Someone
    Big companies can afford higher salaries but it is harder to get noticed. Do you think that a talented programmer or somebody who is training himself to be really good could make more money in smaller companies? I think smaller companies have a lower average, but maybe great programmers can get much more. What do you think?

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  • Is learning C++ a good idea?

    - by chang
    The more I hear and read about C++ (e.g. this: http://lwn.net/Articles/249460/), I get the impression, that I'd waste my time learning C++. I some wrote network routing algorithm in C++ for a simulator, and it was a pain (as expected, especially coming from a perl/python/Java background ...). I'm never happy about giving up on some technology, but I would be happy, if I could limit my knowledge of C-family languages to just C, C# and Objective-C (even OS Xs Cocoa, which is huge and takes a lot of time to learn looks like joy compared to C++ ...). Do I need to consider myself dumb or unwilling, just because I'm not partial to the pain involved learning this stuff? Technologies advance and there will be options other than C++, when deciding on implementation languages, or not? And for speed: If speed were that critical, I'd go for a plain C implementation instead, or write C extensions for much more productive languages like ruby or python ... The one-line version of the above: Will C++ stay such a relevant language that every committed programmer should be familiar with it? [ edit / thank you very much for your interesting and useful answers so far .. ] [ edit / .. i am accepting the top-rated answer; thanks again for all answers! ]

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