Find the Nth occurrence of a character in the given String

Last Updated : 23 Jul, 2021

Given string str, a character ch, and a value N, the task is to find the index of the Nth occurrence of the given character in the given string. Print -1 if no such occurrence exists.

Examples:

Input: str = “Geeks”, ch = ‘e’, N = 2
Output: 2
Input: str = “GFG”, ch = ‘e’, N = 2
Output: -1

Approach:

Traverse the string character by character.
Check for each character if it matches with the given character.
Increment the count by 1, if it matches with the given character.
If the count becomes equal to N, return the latest found index
If the count does not match with N after the traversal, return -1

Below is the implementation of the above approach:

C++

// C++ implementation to find the
// Nth occurrence of a character
 
#include <bits/stdc++.h>
using namespace std;
 
// Function to find the
// Nth occurrence of a character
int findNthOccur(string str,
                 char ch, int N)
{
    int occur = 0;
 
    // Loop to find the Nth
    // occurence of the character
    for (int i = 0; i < str.length(); i++) {
        if (str[i] == ch) {
            occur += 1;
        }
        if (occur == N)
            return i;
    }
    return -1;
}
 
// Driver Code
int main()
{
    string str = "geeks";
    char ch = 'e';
    int N = 2;
    cout << findNthOccur(str, ch, N);
}

Java

// Java implementation to find the
// Nth occurrence of a character
import java.util.*;
 
class GFG
{
 
// Function to find the
// Nth occurrence of a character
static int findNthOccur(String str,
                    char ch, int N)
{
    int occur = 0;
 
    // Loop to find the Nth
    // occurence of the character
    for (int i = 0; i < str.length(); i++)
    {
        if (str.charAt(i) == ch)
        {
            occur += 1;
        }
        if (occur == N)
            return i;
    }
    return -1;
}
 
// Driver Code
public static void main(String[] args)
{
    String str = "geeks";
    char ch = 'e';
    int N = 2;
    System.out.print(findNthOccur(str, ch, N));
}
}
 
// This code is contributed by 29AjayKumar

Python3

# Python3 implementation to find the
# Nth occurrence of a character
 
# Function to find the
# Nth occurrence of a character
def findNthOccur(string , ch, N) :
    occur = 0;
 
    # Loop to find the Nth
    # occurence of the character
    for i in range(len(string)) :
        if (string[i] == ch) :
            occur += 1;
 
        if (occur == N) :
            return i;
     
    return -1;
 
# Driver Code
if __name__ == "__main__" :
 
    string = "geeks";
    ch = 'e';
    N = 2;
    print(findNthOccur(string, ch, N));
 
# This code is contributed by AnkitRai01

C#

// C# implementation to find the
// Nth occurrence of a character
using System;
 
class GFG
{
 
// Function to find the
// Nth occurrence of a character
static int findNthOccur(String str,
                    char ch, int N)
{
    int occur = 0;
 
    // Loop to find the Nth
    // occurence of the character
    for (int i = 0; i < str.Length; i++)
    {
        if (str[i] == ch)
        {
            occur += 1;
        }
        if (occur == N)
            return i;
    }
    return -1;
}
 
// Driver Code
public static void Main(String[] args)
{
    String str = "geeks";
    char ch = 'e';
    int N = 2;
    Console.Write(findNthOccur(str, ch, N));
}
}
 
// This code is contributed by PrinciRaj1992

Javascript

<script>
// Javascript implementation to find the
// Nth occurrence of a character.
 
 
// Function to find the
// Nth occurrence of a character
function findNthOccur(str, ch, N)
{
    var occur = 0;
 
    // Loop to find the Nth
    // occurence of the character
    for (var i = 0; i < str.length; i++) {
        if (str[i] == ch) {
            occur += 1;
        }
        if (occur == N)
            return i;
    }
    return -1;
}
 
var str = "geeks";
    var ch = 'e';
    var N = 2;
    document.write( findNthOccur(str, ch, N));
 
// This code is contributed by SoumikMondal
</script>