string::npos in C++ with Examples
What is string::npos:
- It is a constant static member value with the highest possible value for an element of type size_t.
- It actually means until the end of the string.
- It is used as the value for a length parameter in the string’s member functions.
- As a return value, it is usually used to indicate no matches.
Syntax:
static const size_t npos = -1;
Where, npos is constant static value with the highest possible value for an element of type size_t and it is defined with -1.
Program 1: Below is the C++ program to illustrate the use of string::npos:
C++
// C++ program to demonstrate the use// of string::npos#include <bits/stdc++.h>using namespace std;// Function that using string::npos// to find the index of the occurrence// of any string in the given stringvoid fun(string s1, string s2){ // Find position of string s2 int found = s1.find(s2); // Check if position is -1 or not if (found != string::npos) { cout << "first " << s2 << " found at: " << (found) << endl; } else cout << s2 << " is not in" << "the string" << endl;}// Driver Codeint main(){ // Given strings string s1 = "geeksforgeeks"; string s2 = "for"; string s3 = "no"; // Function Call fun(s1, s2); return 0;} |
Output:
first for found at: 5
Explanation: In the above program string:npos constant is defined with a value of -1, because size_t is an unsigned integral type, and -1 is the largest possible representable value for this type.
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