ACPbE,ex4.4,Strspn() and Strcspn()

#include <stdio.h>
#include <string.h>


int main(void) {
    char    sentence[] = "Hello.  Iam John!";
    char    nonsense[] = "~*%#";
    char    letters[] = "ABCDEdFGHIJKLMNOPQRSTUVWXYZ\
                         abcdefghijklmnopqrstuvwxyz";
    int     numskipped;
    
   
    numskipped = strcspn(sentence, letters);
    printf ("%d chars skipped over until a letter was found.\n", numskipped);
    numskipped = strspn (sentence, letters);
    printf ("%d chars skipped over until a letter was found.\n", numskipped);
    numskipped = strcspn (sentence, nonsense);
    printf ("%d chars skipped over until a letter was found.\n", numskipped);
   
    printf("Hello World!\n");

    return 0;
}