Use "%zu" to print a value of type size_t.

A couple of ugly corner cases:

    const char str[] = "abcd\0efgh";
    printf("length = %zu, size = %zu, value = \"%s\"\n",
           strlen(str), sizeof str, str);

output:

    length = 4, size = 10, value = "abcd"

And:

    const char str[4] = "abcd";
    printf("length = %zu, size = %zu, value = \"%s\"\n",
           strlen(str), sizeof str, str);

This has undefined behavior. (Which is a good reason to let the compiler figure out how big the array has to be. Computers are better at counting things than you are. Let them.)