strchr() function in C/C++

4

strchr() function
In C++, strchr() is a predefined function used for string handling. cstring is the header file required for string functions.

This function Returns a pointer to the last occurrence of a character in a string.
The character whose last occurrence we want to find in passed as the second argument to the function and the string in which we have to find the character is passed as the first argument to the function.
Syntax

char *strrchr(const char *str, int c) 

Here, str is the string and c is the character to be located. It is passed as its int promotion, but it is internally converted back to char.
Application
Given a string in C++, we need to find the last occurrence of a character, lets say ‘a’.

Examples:

Input : string = 'This is a string'
Output :9

Input :string = 'My name is Ayush'
Output :12

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

// C++ program to demonstrate working strchr()
#include <iostream>
#include <cstring>
using namespace std;

int main()
{
  char str[] = "This is a string";
  char * ch = strrchr(str,'a');
  cout << ch - str + 1;
  return 0;
}

Output:

9

C Examples :

// C code to demonstrate the working of
// strrchr()

#include <stdio.h>
#include <string.h>

// Driver function
int main()
{

    // initializing variables
    char st[] = "GeeksforGeeks";
    char ch = 'e';
    char* val;

    // Use of strrchr()
    // returns "ks"
    val = strrchr(st, ch);

    printf("String after last %c is :  %s \n", ch, val);

    char ch2 = 'm';

    // Use of strrchr()
    // returns null
    // test for null
    val = strrchr(st, ch2);

    printf("String after last %c is :  %s ", ch2, val);

    return (0);
}

Output:

String after last e is :  eks 
String after last m is :  (null) 

Practical Application : Since it returns the entire string after last occurrence of a particular character, it can be used to extract the suffix of a string. For e.g to know the entire leading zeroes in a denomination when we know the first number. This example is demonstrated below.

// C code to demonstrate the application of
// strrchr()

#include <stdio.h>
#include <string.h>

// Driver function
int main()
{

    // initializing the denomination
    char denom[] = "Rs 10000000";

    // Printing original string
    printf("The original string is : %s", denom);

    // initializing the initial number
    char first = '1';
    char* entire;

    // Use of strrchr()
    // returns entire number
    entire = strrchr(denom, first);

    printf("\nThe denomination value is : %s ", entire);

    return (0);
}

Output:

The original string is : Rs 10000000
The denomination value is : 10000000 

This article is contributed by Ayush Saxena and Vaishnavi Tripathi. 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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