Cpp - String String Searching

Introduction

You can search strings to find the first or last instance of a substring.

If the string contains the required substring, the position of the substring found by the search is returned.

If not, a pseudo-position npos, or -1, is returned.

The npos constant is defined in the string class, you can reference it as string::npos.

The find() method returns the position at which a substring was first found in the string.

The method requires the substring to be located as an argument.

string s1("this is a test"); 
int first = s1.find("test"); 

You can use the "right find" method rfind() to locate the last occurrence of a substring in a string.

int last = s1.rfind("is"); 

Demo

#include <iostream> 
#include <string> 
using namespace std; 

int main() //from  w w  w.  java2 s .com
{ 
    string s1("this is a test"); 
    int first = s1.find("test"); 
    
    cout << first << endl;    

    int last = s1.rfind("is"); 
        
    cout << last << endl;    
    return 0; 
}

Result