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strstr() in C++
The strstr() function is a predefined function in string.h. It is used to find the occurance of a substring in a string. This process of matching stops at ‘\0’ and does not include it.
Syntax of strstr() is as follows −
char *strstr( const char *str1, const char *str2)
In the above syntax, strstr() finds the first occurance of string str2 in the string str1. A program that implements strstr() is as follows −
Example
#include <iostream>
#include <string.h>
using namespace std;
int main() {
char str1[] = "Apples are red";
char str2[] = "are";
char *ptr;
ptr = strstr(str1, str2);
if(ptr)
cout<<"Occurance of \""<< str2 <<"\" in \""<< str1 <<"\" is at position "<<ptr - str1 + 1;
else
cout<<"There is no occurance of \""<< str2 <<"\" in "<<str1;
return 0;
}Output
The output of the above program is as follows −
Occurance of "are" in "Apples are red" is at position 8
In the above program, str1 and str2 are defined with the values “Apples are red” and “are” respectively. This is given below −
char str1[] = "Apples are red"; char str2[] = "are"; char *ptr;
The pointer ptr points to the first occurrence of “are” in “Apples are red”. This is done using strstr() function. The code snippet for this is given below −
ptr = strstr(str1, str2);
If the pointer ptr contains a value, then the position of str2 in str1 is displayed. Otherwise, it is displayed that there is no occurrence of ptr2 in ptr1. This is shown below −
if(ptr) cout<<"Occurance of \""<< str2 <<"\" in \""<< str1 <<"\" is at position "<<ptr - str1 + 1; else cout<<"There is no occurance of \""<< str2 <<"\" in "<<str1;
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