strstr(): searching for matching string

strstr(main_string, search_string);

#include <stdio.h>
#include <string.h>
int main(void){
   char str[100]="Welcome to C section of plus2net";
   char str_search[20]="to C";
   char *p;
   p = strstr(str,str_search);
   printf("Position :%d",p-str+1);
   return 0;
}

Position :9

#include <stdio.h>
#include <string.h>
int main(void){
   char str[100]="Welcome to plus2net";
   char *p;
   p = strstr(str,'m');
   printf("Position :%d , %s",p-str+1,p);
   return 0;
}

Position :9, to C section of plus2net

Example of string search and replacement using strstr()

#include <stdio.h>
#include <string.h>
int main(void){
   char str[100]="Welcome to C section of plus2net";
   char str_search[20]="to C";
   char *p;
   p = strstr(str,str_search);
   if(p){
    strcpy(p, "to PHP section of plus2net");
    printf("%s",str);
   }else{
   printf(" No matching found ");
   }
   return 0;
}

Welcome to PHP section of plus2net

Example 2: Checking If a Word Exists in a String

Check if a specific word exists in the string using strstr() and print an appropriate message.

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

int main() {
    char str[] = "C programming is fun";
    char *word = "fun";
    
    if (strstr(str, word)) {
        printf("The word '%s' was found in the string.\n", word);
    } else {
        printf("The word '%s' was not found in the string.\n", word);
    }
    
    return 0;
}

The word 'fun' was found in the string.

Example 3: Using strstr() with User Input

This example allows users to input a string and a substring, then checks if the substring is present.

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

int main() {
    char str[100], substr[50];
    
    printf("Enter a string: ");
    fgets(str, sizeof(str), stdin);
    str[strcspn(str, "\n")] = '\0';  // Remove newline
    
    printf("Enter a substring to search for: ");
    fgets(substr, sizeof(substr), stdin);
    substr[strcspn(substr, "\n")] = '\0';  // Remove newline
    
    if (strstr(str, substr)) {
        printf("The substring '%s' was found in the string.\n", substr);
    } else {
        printf("The substring '%s' was not found in the string.\n", substr);
    }
    
    return 0;
}

Enter a string: Welcome to the world of programming
Enter a substring to search for: programming
The substring 'programming' was found in the string.