C库函数 strspn()

#include <stdio.h>

#include <string.h>



int main () {

   int len;

   const char str1[] = "ABCDEFG019874";

   const char str2[] = "ABCD";



   len = strspn(str1, str2);



   printf("Length of initial segment matching %d\n", len );



   return(0);

}