strstr() to find position of first occurrence of search string in a main string through pointer

We can search and get the pointer of first occurance of mathching string by using strstr() string function.

strstr(main_string, search_string);

Output is pointer of first occurrence of matching string. Returns null if searched string is not found.

#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;
}

The output of above code is here

Position :9

In above code, by subtracting the pointer of main string and by adding 1 to it , we will get the position of matching string related to main string.

As we get a pointer by using strstr() , so we can display the string value so rest of the string starting from searched string will be returned.

#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;
}

Output is here

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

String Functions Scripts strrchr() C- Tutorials

strstr(): searching for matching string

Example of string search and replacement using strstr()

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