How to declare the size of an array at runtime in C?

Question

I basically want to the C of equivalent of this (well, just the part with the array, I don\'t need the class and string parsing and all that):

public class E         


        

Answer 1

Unfortunately, many of the answers to this question, including the accepted one, are correct but not equivalent to the OP's code snippet. Remember that operator new[] calls the default constructor for every array element. For POD types like int that do not have a constructor, they are default-initialized (read: zero-initialized, see §8.5 ¶5-7 of The C++ Standard).

I just exchanged malloc (allocate uninitialized memory) for calloc (allocate zeroed memory), so the equivalent to the given C++ snippet would be

#include   /* atoi, calloc, free */

int main(int argc, char *argv[]) {
    size_t size = atoi(argv[1]);
    int *foo;

    /* allocate zeroed(!) memory for our array */
    foo = calloc(sizeof(*foo), size);
    if (foo) {
        /* do something with foo */

        free(foo); /* release the memory */
    }

    return 0;
}

Sorry for reviving this old question but it just didn't feel right to leave without a comment (which I do not have the required rep for) ;-)