c

what does this error mean in c?

#include<stdio.h> #include<ctype.h> int main() { char a,b; FILE *fp; fp=fopen("lext.txt","w"); fprintf(fp,"PLUS"); return 0; } the error i get is this /tmp/ccQyyhxo.o:(.eh_frame+0x11): undefined reference to `__gxx_personality_v0' collect2: ld returned 1 exit status ...

value of c define changes unexpectedly

I have a lot of #define's in my code. Now a weird problem has crept up. I have this: #define _ImmSign 010100 (I'm trying to simulate a binary number) Obviously, I expect the number to become 10100. But when I use the number it has changed into 4160. What is happening here? And how do I stop it? ADDITIONAL Okay, so this is due ...

How to incorporate WebSockets into a Cocoa application

I am developing a Cocoa application which involves a chat element. One approach I've considered is using Websockets to handle client-server communication. This would be particularly desirable because chats will also be displayed on a website, and using Websockets could make the implementation very simple. So: would it be possible to use...

Storing Formatted Data in C

Im trying to add variables to a C char array. Also I have tried sprintf, but it is causing a few other issues within my program. I am looking to do something like this: char* age = "My age is = " + age; I am planning on sending the char array to a socket using send() ...

What is a convenient base for a bignum library & primality testing algorithm?

Hi, I am to program the Solovay-Strassen primality test presented in the original paper on RSA. Additionally I will need to write a small bignum library, and so when searching for a convenient representation for bignum I came across this specification: struct { int sign; int size; int *tab; } bignum; I will also be writing a m...

Can my app arrange a gdb breakpoint or watch?

Is there a way for my code to be instrumented to insert a break point or watch on a memory location that will be honored by gdb? (And presumably have no effect when gdb is not attached.) I know how to do such things as gdb commands within the gdb session, but for certain types of debugging it would be really handy to do it "programma...

string parsing occurrence in c

I have a string as const char *str = "Hello, this is an example of my string"; How could I get everything after the first comma. So for this instance: this is an example of my string Thanks ...

The most efficient way of implementing pow() function in floating point

Hi, I am trying to implement my own version of pow() and sqrt() function as my custom library doesn't have pow()/sqrt() floating point support. Can anyone help? ...

Quick C Style Question

Which is considered better style? int set_int(int *source){ *source = 5; return 0; } int main(){ int x*; set_int(x); } OR int *set_int(){ int *temp = NULL; temp = malloc(sizeof (int)); *temp = 5; return temp; } int main(){ int *x = set_int(); } Coming for a higher level programming background I gotta say I like the secon...

Connect to a website via HTTP in C

i have a C code that parses a file and generates another file for the processed data. i now need to send these files to a web server (website). i guess there way is to do a HTTP POST. but i have never done this in c (Linux gcc compiler in ubuntu). Does anyone know how to do this. i need to a starting point as i have no clue of doing this...

Good Database with C library?

What is a good database with support for C? I want a database that can persist changes when the program is closing and retrieve them when the user starts up the program. I was thinking maybe like SQLite or Berkeley DB. Some documentation would be great too. I just need a database with a library for C. It will be used locally to store sim...

2d array, using calloc in C

Hi, I'm trying to create a 2D array of chars to storage lines of chars. For Example: lines[0]="Hello"; lines[1]="Your Back"; lines[2]="Bye"; Since lines has to be dynamically cause i don't know how many lines i need at first. Here is the code i have: int i; char **lines= (char**) calloc(size, sizeof(char*)); for ( i = 0; i < size; ...

Gui's with Win32 API

I'm wondering what the correct way of creating Gui's in with Win32 API. Right now I just call the CreateWindowEx in my WM_CREATE event, but I don't think this is the right way to do it. Just as an example, what would be the correct way of adding a 100x20 EditField and getting text from it? Would you create it on WM_Create then use GetTex...

how to convert an array of characters in c to a string so as to do string operations on it?

suppose there is a string of characters in an array of d[20] . How to convert to a string d so that i can use it in string functions like strcmp.. ...

Reliable portability for C code without relying on the preprocessor

Relying on the preprocessor and predefined compiler macros for achieving portability seems hard to manage. What's a better way to achieve portability for a C project? I want to put environment-specific code in headers that behave the same way. Is there a way to have the build environment choose which headers to include? I was thinking t...

How can I get bitfields to arrange my bits in the right order?

To begin with, the application in question is always going to be on the same processor, and the compiler is always gcc, so I'm not concerned about bitfields not being portable. gcc lays out bitfields such that the first listed field corresponds to least significant bit of a byte. So the following structure, with a=0, b=1, c=1, d=1, you ...

Include External headers in Eclipse for C

I have some external header files in a separate directory (its the sqlite3.h). I want to be able to use them in my Eclipse CDT project. How would I include the directory to Eclipse? ...

Can I make a "TCP packet modifier" using tun/tap and raw sockets?

I have a Linux application that talks TCP, and to help with analysis and statistics, I'd like to modify the data in some of the TCP packets that it sends out. I'd prefer to do this without hacking the Linux TCP stack. The idea I have so far is to make a bridge which acts as a "TCP packet modifier". My idea is to connect to the applicati...

strstr whole string match

I'm trying to match the whole string and not just part of it. For instance, if the needle is 2, I would like to match just the string 2 and not 20, 02, or 22 or anything related. I'm using strstr as: #include <stdio.h> #include <string.h> int main(int argc, char *argv[]) { FILE *file; char l[BUFSIZ]; int linenumber = 1; c...

CRC for cross platform applications

I wish to use common CRC logic in a VB.NET or C# application as well as on a C/Linux application. I have one C/Linux application that interacts with a webservice (written in C#) and also a web application (written in VB.NET). For some data, I want to add a CRC to the data itself (say a file) from the .NET side and check for the integrity...