How to memcpy() from argv[]?

Question

I want to copy string from argv[0] but I don't know how to get the size of argv[0].

How to do this?

int main(int argc, char* argv[])
{
  char str[20];
  if(argc>0)
      memcpy(str, argv[0], sizeof(argv[0]));
}

Answer 1

Since argv[0] is a string, use strlen.

#include <string.h>

size_t length = strlen (argv[0]) + 1;

memcpy (str, argv[0], length);

By the way, you could also use strcpy, which is more suitable for strings.

#include <string.h>

strcpy (str, argv[0]);

In every case, in order to make sure that your copy won't overflow, you should check whether the size of str is sufficient.

if (sizeof str >= length)
{
  /* Do the copy. */
}
else
{
  /* Report an error, or use dynamic allocation. */
}