C - strstr() function

C strstr() function - Find a substring

Syntax:

char *strstr(const char *string1, const char *string2)

The strstr() function is used to find the first occurrence of string2 in string1. The function ignores the null character (\0) that ends string2 in the matching process.

Parameters:

Return value from strstr()

• Returns a pointer to the first occurrence of string2 in string1, or NULL if string2 doesn't appear in string1.
• If string2 points to a string of zero length, the function returns string1.

Example: strstr() function

#include <string.h>
#include <stdio.h>
 
int main(void)
{
   char string1[] = "C Programming";
   char string2[] = "ming";
   char *result;
   printf("String1 = %s",string1);
   printf("\nString2 = %s",string2);
   result = strstr(string1,string2);
   printf("\nFind the first occurrence of string2 in string1 = %s\n", result);
   char string3[] = "mng";
   result = strstr(string1,string3);
   printf("\n\nString1 = %s",string1);
   printf("\nString3 = %s",string3);
   printf("\n\Find the first occurrence of string3 in string1 = %s\n", result);
}

Output:

String1 = C Programming
String2 = ming
Find the first occurrence of string2 in string1 = ming


String1 = C Programming
String3 = mng
Find the first occurrence of string3 in string1 = (null)

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