I’m making a C program where I need to get the directory that the program is started from. This program is written for UNIX computers. I’ve been looking at opendir() and telldir(), but telldir() returns a off_t (long int), so it really doesn’t help me. How can I get the current path in a string … Read more
I saw the “new type” BOOL (YES, NO). I read that this type is almost like a char. For testing I did : NSLog(@”Size of BOOL %d”, sizeof(BOOL)); NSLog(@”Size of bool %d”, sizeof(bool)); Good to see that both logs display “1” (sometimes in C++ bool is an int and its sizeof is 4) So I … Read more
I’m reading up on pthread.h; the condition variable related functions (like pthread_cond_wait(3)) require a mutex as an argument. Why? As far as I can tell, I’m going to be creating a mutex just to use as that argument? What is that mutex supposed to do? 10 Answers 10
I’m trying to create a hello world project for Linux dynamic libraries (.so files). So I have a file hello.c: #include <stdio.h> void hello() { printf(“Hello world!\n”); } How do I create a .so file that exports hello(), using gcc from the command line? 1 Answer 1
I know you can print with printf() and puts(). I can also see that printf() allows you to interpolate variables and do formatting. Is puts() merely a primitive version of printf(). Should it be used for every possible printf() without string interpolation? 10 Answers 10
On a Unix system, where does gcc look for header files? I spent a little time this morning looking for some system header files, so I thought this would be good information to have here. 9 Answers 9
Does an Integer variable in C occupy 2 bytes or 4 bytes? What are the factors that it depends on? Most of the textbooks say integer variables occupy 2 bytes. But when I run a program printing the successive addresses of an array of integers it shows the difference of 4. 13 Answers 13
I have the following boxes: a) A Windows box with Eclipse CDT, b) A Linux box, accessible for me only via SSH. Both the compiler and the hardware required to build and run my project is only on machine B. I’d like to work “transparently” from a Windows box on that project using Eclipse CDT … Read more
In errno.h, this variable is declared as extern int errno; so my question is, is it safe to check errno value after some calls or use perror() in multi-threaded code. Is this a thread safe variable? If not, then whats the alternative ? I am using linux with gcc on x86 architecture. 8 Answers 8
In C, I know I can dynamically allocate a two-dimensional array on the heap using the following code: int** someNumbers = malloc(arrayRows*sizeof(int*)); for (i = 0; i < arrayRows; i++) { someNumbers[i] = malloc(arrayColumns*sizeof(int)); } Clearly, this actually creates a one-dimensional array of pointers to a bunch of separate one-dimensional arrays of integers, and “The … Read more