C/string.h/strstr

strstr: Returns a pointer to the first occurrence of *str2 in *str1 or a null pointer if there str2 is not part of str1

<source lang="cpp">

//Declaration: char *strstr(const char *str1, const char *str2); //Return: It returns a null pointer if no match is found.

 #include <string.h>
 #include <stdio.h>
 int main(void)
 {
   char *p;
   p = strstr("this is a test", "is");
   printf(p);
   return 0;
 }
        

/* is is a test*/

      </source>