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  • How do I split up a long value (32 bits) into four char variables (8bits) using C?

    - by Jordan S
    I have a 32 bit long variable, CurrentPosition, that I want to split up into 4, 8bit characters. How would I do that most efficiently in C? I am working with an 8bit MCU, 8051 architectecture. unsigned long CurrentPosition = 7654321; unsigned char CP1 = 0; unsigned char CP2 = 0; unsigned char CP3 = 0; unsigned char CP4 = 0; // What do I do next? Should I just reference the starting address of CurrentPosition with a pointer and then add 8 two that address four times? It is little Endian. ALSO I want CurrentPosition to remain unchanged.

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  • typedef declaration syntax

    - by mt_serg
    Some days ago I looked at boost sources and found interesting typedef. There is a code from "boost\detail\none_t.hpp": namespace boost { namespace detail { struct none_helper{}; typedef int none_helper::*none_t ; } // namespace detail } // namespace boost I didn't see syntax like that earlier and can't explain the sense of that. This typedef introduces name "none_t" as pointer to int in boost::detail namespace. What the syntax is? And what difference between "typedef int none_helper::*none_t" and for example "typedef int *none_t" ?

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  • How to make an NSURL that contains a | (pipe character)?

    - by aks
    Hi all, I am trying to access google maps' forward geocoding service from my iphone app. When i try to make an NSURL from a string with a pipe in it I just get a nil pointer. NSURL *searchURL = [NSURL URLWithString:@"http://maps.google.com/maps/api/geocode/json?address=6th+and+pine&bounds=37.331689,-122.030731|37.331689,-122.030731&sensor=false"]; I dont see any other way in the google api to send bounds coordinates with out a pipe. Any ideas about how I can do this?

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  • Unexpected key-value behavior in a Core Data Context

    - by ????
    If I create an array of strings (via key-value coding) containing the names of a Managed Object entity's attributes which are stored in the App Delegate the first time, I get an array of NSStrings without any problems. If I subsequently make the same call later from the same entry point in code, that same collection becomes an array of NULL objects- even though nothing in the Core Data Context has changed. One unappealing work-around involves re-creating the string array every time, but I'm wondering if anyone has a guess as to what's happening behind the scenes. // Return an array of strings with the names of attributes the Activity entity - (NSArray *)activityAttributeNames { #pragma mark ALWAYS REFRESH THE ENTITY NAMES? //if (activityAttributeNames == nil) { // Create an entity pointer for Activity NSEntityDescription *entity = [NSEntityDescription entityForName:@"Activity" inManagedObjectContext:managedObjectContext]; NSArray *entityAttributeArray = [[NSArray alloc] initWithArray:[[entity attributesByName] allValues]]; // Extract the names of the attributes with Key-Value Coding activityAttributeNames = [entityAttributeArray valueForKeyPath:@"name"]; [entityAttributeArray release]; //} return activityAttributeNames; }

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  • Writing a PHP web crawler using cron

    - by Horse
    Hi all I have written myself a web crawler using simplehtmldom, and have got the crawl process working quite nicely. It crawls the start page, adds all links into a database table, sets a session pointer, and meta refreshes the page to carry onto the next page. That keeps going until it runs out of links That works fine however obviously the crawl time for larger websites is pretty tedious. I wanted to be able to speed things up a bit though, and possibly make it a cron job. Any ideas on making it as quick and efficient as possible other than setting the memory limit / execution time higher?

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  • Efficiently remove points with same slope

    - by Ram
    Hi, In one of mine applications I am dealing with graphics objects. I am using open source GPC library to clip/merge two shapes. To improve accuracy I am sampling (adding multiple points between two edges) existing shapes. But before displaying back the merged shape I need to remove all the points between two edges. But I am not able to find an efficient algorithm that will remove all points between two edges which has same slope with minimum CPU utilization. Currently all points are of type PointF Any pointer on this will be a great help.

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  • Designing an API with compile-time option to remove first parameter to most functions and use a glob

    - by tomlogic
    I'm trying to design a portable API in ANSI C89/ISO C90 to access a wireless networking device on a serial interface. The library will have multiple network layers, and various versions need to run on embedded devices as small as an 8-bit micro with 32K of code and 2K of data, on up to embedded devices with a megabyte or more of code and data. In most cases, the target processor will have a single network interface and I'll want to use a single global structure with all state information for that device. I don't want to pass a pointer to that structure through the network layers. In a few cases (e.g., device with more resources that needs to live on two networks) I will interface to multiple devices, each with their own global state, and will need to pass a pointer to that state (or an index to a state array) through the layers. I came up with two possible solutions, but neither one is particularly pretty. Keep in mind that the full driver will potentially be 20,000 lines or more, cover multiple files, and contain hundreds of functions. The first solution requires a macro that discards the first parameter for every function that needs to access the global state: // network.h typedef struct dev_t { int var; long othervar; char name[20]; } dev_t; #ifdef IF_MULTI #define foo_function( x, a, b, c) _foo_function( x, a, b, c) #define bar_function( x) _bar_function( x) #else extern dev_t DEV; #define IFACE (&DEV) #define foo_function( x, a, b, c) _foo_function( a, b, c) #define bar_function( x) _bar_function( ) #endif int bar_function( dev_t *IFACE); int foo_function( dev_t *IFACE, int a, long b, char *c); // network.c #ifndef IF_MULTI dev_t DEV; #endif int bar_function( dev_t *IFACE) { memset( IFACE, 0, sizeof *IFACE); return 0; } int foo_function( dev_t *IFACE, int a, long b, char *c) { bar_function( IFACE); IFACE->var = a; IFACE->othervar = b; strcpy( IFACE->name, c); return 0; } The second solution defines macros to use in the function declarations: // network.h typedef struct dev_t { int var; long othervar; char name[20]; } dev_t; #ifdef IF_MULTI #define DEV_PARAM_ONLY dev_t *IFACE #define DEV_PARAM DEV_PARAM_ONLY, #else extern dev_t DEV; #define IFACE (&DEV) #define DEV_PARAM_ONLY void #define DEV_PARAM #endif int bar_function( DEV_PARAM_ONLY); // I don't like the missing comma between DEV_PARAM and arg2... int foo_function( DEV_PARAM int a, long b, char *c); // network.c #ifndef IF_MULTI dev_t DEV; #endif int bar_function( DEV_PARAM_ONLY) { memset( IFACE, 0, sizeof *IFACE); return 0; } int foo_function( DEV_PARAM int a, long b, char *c) { bar_function( IFACE); IFACE->var = a; IFACE->othervar = b; strcpy( IFACE->name, c); return 0; } The C code to access either method remains the same: // multi.c - example of multiple interfaces #define IF_MULTI #include "network.h" dev_t if0, if1; int main() { foo_function( &if0, -1, 3.1415926, "public"); foo_function( &if1, 42, 3.1415926, "private"); return 0; } // single.c - example of a single interface #include "network.h" int main() { foo_function( 11, 1.0, "network"); return 0; } Is there a cleaner method that I haven't figured out? I lean toward the second since it should be easier to maintain, and it's clearer that there's some macro magic in the parameters to the function. Also, the first method requires prefixing the function names with "_" when I want to use them as function pointers. I really do want to remove the parameter in the "single interface" case to eliminate unnecessary code to push the parameter onto the stack, and to allow the function to access the first "real" parameter in a register instead of loading it from the stack. And, if at all possible, I don't want to have to maintain two separate codebases. Thoughts? Ideas? Examples of something similar in existing code? (Note that using C++ isn't an option, since some of the planned targets don't have a C++ compiler available.)

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  • What will be the setup process for website development?

    - by Vijay Shanker
    Hi, I want to create a simple site for my personal usage. And this only in python based technologies. So I want to get a expert oponian on this topic. What should i used as platform? I did a search for available options and found Django, grok, web2py and many more of these. Which one a novice use should use? If I choose to use only the basic python scripts then what option i have to work on? http://wiki.python.org/moin/WebBrowserProgramming. This link on python site confused me more, instead of solving my curiosity about the topic. Please give some pointer to accurate and easy to understand reading materials. I have got a idea of developing java based web applications using either spring-webmvc and struts. Can I relate Java process to python process for web development?

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  • menuitem id in xml format can't be an integer? huh. really?

    - by misbell
    ok, in menu.add, you add an integer menuitem id. But when you specify the menu in xml, @+id can't take an integer, so you can't test the id for the menu item as an integer in a switch statement. What obvious thing am I missing, because surely an inconsistency this bone-stupid couldn't have passed muster with all those wonderful geniuses at Google. on top of that, when I give the menu item a name like "@+id/myMenuItem", item.getItemId() returns an integer, a long one, which I guess is a representation of the hex pointer. M

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  • What does this error mean when using OpenAL in the iPhone Simulator?

    - by mystify
    I'm getting this in the console, when creating my OpenAL Sources and Buffers: Cannot find executable for CFBundle/CFPlugIn 0xf530d0 </Library/Audio/Plug-Ins/HAL/Hear.plugin> (not loaded) 2010-05-05 17:11:13.934 Testproj[43173:207] Cannot find function pointer HearCFPlugInFactory for factory 5268FAAB-0147-4272-93FD-4D60A2433C1C in CFBundle/CFPlugIn 0xf430d0 </Library/Audio/Plug-Ins/HAL/Hear.plugin> (not loaded) However, the sounds play nicely. I think HAL is not available on the iPhone, it's just on Mac OS X, right? Do you guys also get that error in the simulator when using OpenAL?

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  • typedef resolution rule

    - by kumar_m_kiran
    Hi All, Can you Please tell me the resolution rule involved in resolving the meaning of the variable in a typedef. Any link related to the same will be very useful. Example #typedef string* pstring; const pstring parr; Here confusion arises whether const'ness is for pointer or the content. Now based on what thumb rule do can we start resolving the above interpretation of the pstring?. Smilarly, If I have a very complex typedef'ed variable, like #typedef void (func*)()(int), I should be able to resolve it using the thumb rule. Thanks in advance for your suggestions

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  • Performing time consuming operation on STL container within a lock

    - by Ashley
    I have an unordered_map of an unordered_map which stores a pointer of objects. The unordered map is being shared by multiple threads. I need to iterate through each object and perform some time consuming operation (like sending it through network etc) . How could I lock the multiple unordered_map so that it won't blocked for too long? typedef std::unordered_map<string, classA*>MAP1; typedef std::unordered_map<int, MAP1*>MAP2; MAP2 map2; pthread_mutex_lock(&mutexA) //how could I lock the maps? Could I reduce the lock granularity? for(MAP2::iterator it2 = map2.begin; it2 != map2.end; it2++) { for(MAP1::iterator it1 = *(it2->second).begin(); it1 != *(it2->second).end(); it1++) { //perform some time consuming operation on it1->second eg sendToNetwork(*(it1->second)); } } pthread_mutex_unlock(&mutexA)

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  • Cannot implicitly convert type 'char*' to 'bool'

    - by neeraj
    i was trying to passing pointer value in the function , i really got stuck here I am a beginner , not getting what value should be put this is programme from the reference of the book "Cracking the coding interview " By Gayle Laakmann McDowell, class Program { unsafe void reverse(char *str) { char* end = str; char tmp; if (str) //Cannot implicitly convert type 'char*' to 'bool' { while(*end) //Cannot implicitly convert type 'char*' to 'bool' { ++end; } --end; while(str<end) { tmp = *str; *str+= *end; *end-= tmp; } } } public static void Main(string[] args) { } }

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  • Confused about "override" vs. "new" in C#

    - by iTayb
    I'm having the following classes: class Base { public virtual void Print() { Console.WriteLine("Base"); } } class Der1 : Base { public new virtual void Print() { Console.WriteLine("Der1"); } } class Der2 : Der1 { public override void Print() { Console.WriteLine("Der2"); } } This is my main method: Base b = new Der2(); Der1 d1 = new Der2(); Der2 d2 = new Der2(); b.Print(); d1.Print(); d2.Print(); The output is Base, Der2, Der2. As far as I know, Override won't let previous method to run, even if the pointer is pointing to them. So the first line should output Der2 as well. However Base came out. How is it possible? How the override didn't work there?

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  • A programming language for teaching data structures and algorithms with? [closed]

    - by Andreas Grech
    Possible Duplicate: Choice of programming language for learning data structures and algorithms Teachers have different opinions on what programming language they would choose to teach data structures and algorithms with. Some would prefer a lower level language such as C because it allows the student to learn more about what goes on beyond the abstractions in terms of memory allocation and deallocation and pointers and pointer arithmetic. On the other hand, others would say that they would prefer a higher level language like Java because it allows the student to learn more about the concepts of the structures and the algorithm design rather than 'waste time' and fiddle around with memory segmentation faults and all the blunders that come with languages where memory management is manual. What is your take on this issue? And also, please post any references you may know of that also discuss this argument.

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  • Marshalling a C structure to C#

    - by Hilbert
    Hi, I don't know how to marshall this structure in Mono. typedef struct rib_struct { rib_used_t used; rib_status_t status; rib_role_t role; uint8_t conf; rib_dc_t *pending; pthread_mutex_t mutex; pthread_cond_t cond; rib_f_t *props; } rib_t; And for example, rib_dc_t is like: typedef struct rib_dc_struct { uint16_t id; uint8_t min_id; uint8_t conf; struct rib_dc_struct *next; } rib_dc_t; I don't know how to marshall the pthread structures. And the pointers... should I use IntPtr or a managed structures? How to mashall the pointer in the last struct to the struct itself? Thanks in adanvaced

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  • Send copy of class to view class so it can render him? ( iPhone )

    - by Johannes Jensen
    I'm making a game for the iPhone, and I have a class called Robot. Then I have a class called View, which renders everything. I want to send a copy of my Robot, which I defined in my ViewController, and I send it to gameView (which is View *gameView), like this: robot = [Robot new]; [gameView setRobot: [robot copy]]; I tried to make a copy but that didn't work, I could also do it with a pointer to Robot (&robot) but sometimes it just crashes ? I tried this in my View.h @interface definition: @property (copy) Robot* robot; but I get the error /RobotsAdventure/Classes/View.h:24: error: setter '-robot' argument type does not match property type :/ Help? I'm pretty new at this, heh.

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  • Interrupting `while loop` with keyboard in Cython

    - by linello
    I want to be able to interrupt a long function with cython, using the usual CTRL+C interrupt command. My C++ long function is repeatedly called inside a while loop from Cython code, but I want to be able, during the loop, to send an "interrupt" and block the while loop. The interrupt also should wait the longFunction() to finish, so that no data are lost or kept in unknown status. This is one of my first implementation, which obviously doesn't work: computed=0; print "Computing long function..." while ( computed==0 ): try: computed = self.thisptr.aLongFunction() except (KeyboardInterrupt, SystemExit): computed=1 print '\n! Received keyboard interrupt.\n' break; (p.s. self.thisptr is the pointer to the current class which implements aLongFunction() )

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  • Copying pointers in C++

    - by tunnuz
    Hello, I have a class A containing two pointers to objects of another class B. I want to initialize one pointer or the other depending on which one is passed to init(), which also takes other parameters. My situation is thus the following: class A { public: A(); init(int parameter, int otherParameter, B* toBeInitialized); protected: B* myB; B* myOtherB; }; Now my point is that I want to call init() as: init(640, 480, this->myB); or init(640, 480, this->myOtherB); Now, my init is implemented as: void init( int parameter, int otherParameter, B* toBeInitialized ) { toBeInitialized = someConstructorFunction(parameter, otherParameter); } The problem is that the two pointers are not initialized, I suspect that toBeInitialized is overwritten, but the original parameter is not modified. I am doing something wrong? Should I use references to pointers? Thank you Tommaso

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  • pass by reference but reference to data and not to variable

    - by dorelal
    This is psesudo code. In what programming language this is possible ? def lab(input) input = ['90'] end x = ['80'] lab(x) puts x #=> value of x has changed from ['80'] to ['90] I have written this in ruby but in ruby I get the final x value of 80 because ruby is pass-by-reference. However what is passed is the reference to the data held by x and not pointer to x itself same is true in JavaScript. So I am wondering if there is any programming language where the following is true.

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  • Openning an App on click of link in email in android?

    - by Amit
    I have a strange requirement for my project.. Suppose I have an app say XYZ installed in an android phone and than I receive an email from the mail server which contains a link like http://XYZ.com/?params(i.e. X=1&Y=2&Z=3) now on click of this link I want to open the XYZ app if it is installed in the phone and in the Activity I would like to get these parameters X,Y and Z and if the app is not installed user should be redirected to play store for downloading XYZ app and after installation app takes charge and behaves as if it was already installed (Opening the first activity with those parameters). How can I achieve that ? I have no idea where to start so even the smallest pointer in right direction will be of great help.

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  • Unable to get Processor Speed in Device

    - by mukesh
    Hi i am using QueryperformanceFrequency to get the No of cycle i.e processor speed. But it is showing me the wornd value. It is written in the specicfication is the Processor is about 400MHz, but what we aregetting through code is something 16MHz. Please porvide any pointer : The code for Wince device is: enter code here LARGE_INTEGER FrequnecyCounter; QueryPerformanceFrequency(&FrequnecyCounter); CString temp; temp.Format(L"%lld",FrequnecyCounter.QuadPart)`AfxMessageBox(temp); Thanks, Mukesh

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  • How can i use listDictionary?

    - by Phsika
    i can fill my listdictinary but, if running error returns to me in " foreach (string ky in ld.Keys)"(invalid operation Exception was unhandled) Error Detail : After creating a pointer to the list of sample collection has been changed. C# ListDictionary ld = new ListDictionary(); foreach (DataColumn dc in dTable.Columns) { MessageBox.Show(dTable.Rows[0][dc].ToString()); ld.Add(dc.ColumnName, dTable.Rows[0][dc].ToString()); } foreach (string ky in ld.Keys) if (int.TryParse(ld[ky].ToString(), out QuantityInt)) ld[ky] = "integer"; else if(double.TryParse(ld[ky].ToString(), out QuantityDouble)) ld[ky]="double"; else ld[ky]="nvarchar";

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  • one document.createElement, append it twice, only shows once

    - by Sirber
    I have a button I want to use in the beginning and the end of the page: var button_save = document.createElement('button'); $("#compteurs").append(button_save); [...] $("#compteurs").append(button_save); but it only appear at the end of the page. If I remove it from the bottom of the page, it appear at the begining of page. It's a kind of pointer. Is there a way to create the button only once and use it twice? Thanks!

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  • Best way to track impressions/clicks in a bespoke advertisement system?

    - by Martin Bean
    I've been asked to create a bespoke advertisement system despite suggesting open source alternatives such as OpenX and DoubleClick for Publishers (the former Google Ad Manager). I've got the basics of the system set up, i.e. uploading creatives, creating positions and a mechanism to place creatives within positions; however, the area I'm stuck with is impression and click tracking. At the moment an impression and click is stored with the creative, but this then means impressions/clicks can't be queried. For example, we can't find how many impressions were in position x between date y and date z. How would I go about storing that kind of data? My theory was store the creative ID, position ID and timestamp in a database table, but given the amount of traffic the site has this would produce a very large database very quickly. If any one could give me a pointer or two, that would be great.

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