Random Numbers in C

1)  In the below program everytime program is run different numbers are generated.

        #include <stdio.h>
        int main()
        {
            srand(time(NULL));
            printf("%d\n", rand());
            return 0;
        }


2)      
2) the output of this C code is to print an integer between 0-999 including 0 and 999.

        #include <stdio.h>
        #include <stdlib.h>
        int main()
        {
            printf("%d\n", rand() % 1000);
            return 0;
        }