sorting - How do I sort the elements of argv in C?

Question

I am trying to alphabetically sort the elements of argv.

The following line of code is giving me problems:

qsort(argv[optind], argc - optind, sizeof(argv[optind]), sort);

Specifically, the last argument is giving me trouble, the comparison function, which is given below:

int
sort(const void *a, const void * b)
{    
    return(strcmp( (char*)a, (char*)b ));
}

At the moment, it compiles fine, but I end up getting a segmentation fault when I run it.

Answer 1

The first argument should be argv+optind, as this is the address of the first element in the sequence to be sorted.