accessing a file
On Linux, how can I make sure that my program is the only one accessing a file? ...
c
Why does n++ execute faster than n=n+1 ?
In C language, Why does n++ execute faster than n=n+1? (int n=...; n++;) (int n=...; n=n+1;) Our instructor asked that question in today's class. (this is not homework) ...
when to use strncpy or memmove
Hello, gcc 4.4.4 c89 I have always used strncpy to copy strings. I have never really used memmove or memcpy very much. However, I am just wondering when would you decide whether to use strncpy, memmove, or memcpy? The code I am writing is for a client/server application. In the documentation they use bcopy. However, could I do the sam...
Simple C question
HI all. I am trying to make little program that reads data from file which has name of user and some data for that user. I am new on C , and how can i calculate this data for its user?line by line reading and adding each char in array? And how can I read line? is there any function? And how can I use this each line users like object?I...
Programming /open source / Beginner
Possible Duplicate: How to get involved in an open source project I m a CS UG student Wanaa know How to participate in open source projects ? Which one will be good for beginner in C ,Java ? Interests include web appln and db ? exactly wana ask is that how source forge will help for starting ... I found the codes very complic...
change the default window font in a win32 windows project
I am creating a GUI application using C and Win32 api. I would like to know how we can change the default font of the Main window to thaoma. I am comming from .NET background. In .NET if we change the font of parent control then automatically the child controls inherits that font.... Is there away similar to it or do we need to manually ...
C++ Structure within itself?
I've been trying to port this code to python, but there is something I do not quite understand in C++ (I do know a bit of C++ but this is beyond me): typedef struct huffnode_s { struct huffnode_s *zero; struct huffnode_s *one; unsigned char val; float freq; } huffnode_t; What I don't get is how huffnode_s can be within...
Warping Images using cvWarpPerspective Results in Some Parts of the images out of the viewable area
Hi, I am trying to stich two images together. In order to do so I extracted sift features and find matches on the two images using this C implementation. http://web.engr.oregonstate.edu/~hess/index.html After that I found the homography matrix using the matched points. http://www.ics.forth.gr/~lourakis/homest/ But if I use this ...
overflow technique in stack
int main(void) { problem2(); } void doit2(void) { int overflowme[16]; //overflowme[37] =0; } void problem2(void) { int x = 42; doit2(); printf("x is %d\n", x); printf("the address of x is 0x%x\n", &x); } Would someone help me understand why overflowme[37] =0; from the doit2 function will overwrite the value...
Force blocking read after EAGAIN?
I have a file descriptor that is open for reading which may be non-blocking. What I need to do is simply read all data until reaching EOF and write that data to a writable file descriptor. As the process that performs this copying is not "aware" of anything that is going on around it, I don't think that I can do something useful while wa...
TrackMouseEvent not working
Basically I call TrackMouseEvent in my WM_CREATE then I call it again after a WM_MOUSELEAVE but this freezes up my program. Where should I be sticking it? Thanks ...
Unit testing UDP socket handling code
Are there any 'good' ways to cause a thread waiting on a recvfrom() call to become unblocked and return with an error? The motivation for this is to write unit tests for a system which includes a unit that reads UDP datagrams. One of the branches handles errors on the recvfrom call itself. The code isn't required to distinguish between...
compile with -ansi -pedantic -Wall switches automatically with gcc
We are required to compile C source codes using gcc in this manner: gcc -ansi -pedantic -Wall program.c I'm wondering how can I 'automate' this so when I enter: gcc program.c It will automatically compile with the 3 switches. Is this possible? ...
difference fixed width strings and zero-terminated strings
Hello, gcc 4.4.4 c89 I got into a recent discussion about "fixed width strings" and "zero terminated strings". When I think about this. They seem to be the same thing. A string with a terminating null. i.e. char *name = "Joe bloggs"; Is a fixed width string that cannot be changed. And also has a terminating null. Also in the dis...
Dedicating all processor power to a task
Let's say we have a very processor-intensive task at hand which could be effectively parallelized. How can we dedicate all or almost all available processor power to performing that task? The task could be a variety of things, and iterative Fibonacci number generation that saves recorded numbers would be just one example. ...
Clever ways of implementing different data structures in C & data structures that should be used more often
What are some clever (not ordinary) ways of implementing data structures in C, and what are some data structures that should be used more often? For example, what is the most effective way (generating minimal overhead) to implement a directed and cyclic graph with weighted edges in C? I know that we can store the distances in an array a...
bluetooth application devlopment
i want to devlop bluetooth(c/c++) applications in linux can any one help me how to and where to start ? can any one one provide me proper tutorial ?? ...
What is the difference between kernel and user mode programming?
I would like to know how a kernel programmer thinks about memory vs user mode programmer. I would also like to know a few more differences between kernel programming and user mode programming. ...
where did the _syscallN macros go in <linux/unistd.h>?
It used to be the case that if you needed to make a system call directly in linux without the use of an existing library, you could just include <linux/unistd.h> and it would define a macro similar to this: #define _syscall3(type,name,type1,arg1,type2,arg2,type3,arg3) \ type name(type1 arg1,type2 arg2,type3 arg3) \ { \ long __res; \ __a...
a macro question for c language (#define)
I am reading source code of hoard memory allocator, and in the file of gnuwrapper.cpp, there are the following code #define CUSTOM_MALLOC(x) CUSTOM_PREFIX(malloc)(x) What's the meaning of CUSTOM_PREFIX(malloc)(x)? is CUSTOM_PREFIX a function? But as a function it didn't defined anywhere. If it's variable, then how can we use v...