strchr() function in C++ and its applications

2

In C++, strchr() is a predefined function used for finding occurrence of a character in a string. It is present in cstring header file.

Syntax

// Returns pointer to the first occurrence
// of c in str[]
char *strchr(const char *str, int c) 

Note that c is passed as its int promotion, but it is internally treated as char.

Application
Given a string in c++, we need to find the first occurrence of a character, lets say ‘a’.
Examples:

Input : str[] = 'This is a string'
Output : 9

Input : str[] = 'My name is Ayush'
Output : 4

Algorithm
1. Pass the given string in the strchr() function and mention the character you need to point.
2. The function return a value, print the value.

// CPP program to find position of a character
// in a given string.
#include <iostream>
#include <cstring>
using namespace std;

int main()
{
    char str[] = "My name is Ayush";
    char* ch = strchr(str, 'a');
    cout << ch - str + 1;
    return 0;
}

Output:

5

strch() function can also be used to check the presence of a character in a strinG. The input consists of a character we want to check, if it exists in the string.
For example – Lets check if the characters A and z are present in the string – “My name is Ayush”

Input : str[] = 'My name is Ayush', 
        ch1 = 'A', ch2 = 'z'
Output : A is present in the string
         z is not present in the string

Algorithm
1. Pass the given string in the strchr() function with the character as the second parameter and check if the value returned is not null
2. If the function returns a NULL value, this means that the string does not contains the character, so, print the required statement.
3. Else if the function does not returns a NULL value, this means that the string contains the character, so, print the required statement.

// CPP program to demonstrate working of strchr()
#include <iostream>
#include <cstring>
using namespace std;
// Driver code
int main()
{
    char str[] = "My name is Ayush";
    char ch = 'A', ch2 = 'z';
    if (strchr(str, ch) != NULL)
        cout << ch << " "
             << "is present in string" << endl;
    else
        cout << ch << " "
             << "is not present in string" << endl;
    if (strchr(str, ch2) != NULL)
        cout << ch2 << " "
             << "is present in string" << endl;
    else
        cout << ch2 << " "
             << "is not present in string" << endl;
    return 0;
}

Output:

A is present in the string
z is not present in the string

This article is contributed by Ayush Saxena. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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