Count occurrences of a word in string

Last Updated : 04 Nov, 2023

You are given a string and a word your task is that count the number of occurrences of the given word in the string and print the number of occurrences of the word.

Examples:

Input : string = "GeeksforGeeks A computer science portal for geeks"
word = "portal"
Output : Occurrences of Word = 1 Time
Input : string = "GeeksforGeeks A computer science portal for geeks"
word = "technical" 
Output : Occurrences of Word = 0 Time

Approach:

First, we split the string by spaces in a

Then, take a variable count = 0 and in every true condition we increment the count by 1

Now run a loop at 0 to length of string and check if our string is equal to the word

if condition is true then we increment the value of count by 1 and in the end, we print the value of count.

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Below is the implementation of the above approach :

C++

// C++ program to count the number
// of occurrence of a word in
// the given string
#include <bits/stdc++.h>
using namespace std;
 
int countOccurrences(char *str, 
                    string word)
{
    char *p;
 
    // split the string by spaces in a
    vector<string> a;
 
    p = strtok(str, " ");
    while (p != NULL)
    {
        a.push_back(p);
        p = strtok(NULL, " ");
    }
 
    // search for pattern in a
    int c = 0;
    for (int i = 0; i < a.size(); i++)
 
        // if match found increase count
        if (word == a[i])
            c++;
    return c;
}
 
// Driver code
int main()
{
    char str[] = "GeeksforGeeks A computer science portal for geeks ";
    string word = "portal";
    cout << countOccurrences(str, word);
    return 0;
}
 
// This code is contributed by
// sanjeev2552

C

// C program to count the number
// of occurrence of a word in
// the given string
#include <stdio.h>
#include <string.h>
 
int countOccurrences(char *str, char *word)
{
    char *p;
 
    // split the string by spaces in a
    char *a[300];
      int index=0;
 
    p = strtok(str, " ");
    while (p != NULL)
    {
        a[index++]=(p);
        p = strtok(NULL, " ");
    }
 
    // search for pattern in a
    int c = 0;
    for (int i = 0; i < index; i++)
        // if match found increase count
        if (strcmp(word , a[i])==0){
            c++;
        }
    return c;
}
 
// Driver code
int main()
{
    char str[] = "GeeksforGeeks A computer science portal for geeks ";
    char word[] = "portal";
    printf("%d",countOccurrences(str, word));
    return 0;
}

Java

// Java program to count the number 
// of occurrence of a word in
// the given string
import java.io.*;
 
class GFG {
 
static int countOccurrences(String str, String word) 
{
    // split the string by spaces in a
    String a[] = str.split(" ");
 
    // search for pattern in a
    int count = 0;
    for (int i = 0; i < a.length; i++) 
    {
    // if match found increase count
    if (word.equals(a[i]))
        count++;
    }
 
    return count;
}
 
// Driver code
public static void main(String args[]) 
{
    String str = "GeeksforGeeks A computer science portal for geeks ";
    String word = "portal";
    System.out.println(countOccurrences(str, word));
}
}
 
/*This code is contributed by Nikita Tiwari.*/

Python 3

# Python program to count the number of occurrence 
# of a word in the given string
 
def countOccurrences(str, word):
     
    # split the string by spaces in a
    a = str.split(" ")
 
    # search for pattern in a
    count = 0
    for i in range(0, len(a)):
         
        # if match found increase count 
        if (word == a[i]):
           count = count + 1
            
    return count       
 
# Driver code
str ="GeeksforGeeks A computer science portal for geeks  "
word ="portal"
print(countOccurrences(str, word))

C#

// C# program to count the number 
// of occurrence of a word in
// the given string
using System;
 
class GFG 
{
static int countOccurrences(string str,
                           string word) 
{
    // split the string by spaces
    string[] a = str.Split(' ');
 
    // search for pattern in string
    int count = 0;
    for (int i = 0; i < a.Length; i++) 
    {
         
    // if match found increase count
    if (word.Equals(a[i]))
        count++;
    }
 
    return count;
}
 
// Driver code
public static void Main() 
{
    string str = "GeeksforGeeks A computer science portal for geeks ";
    string word = "portal";
    Console.Write(countOccurrences(str, word));
}
}
 
// This code is contributed
// by ChitraNayal

Javascript

<script>
 
// Javascript program to count the number
// of occurrence of a word in
// the given string
     
    function countOccurrences(str,word)
    {
        // split the string by spaces in a
    let a = str.split(" ");
  
    // search for pattern in a
    let count = 0;
    for (let i = 0; i < a.length; i++)
    {
    // if match found increase count
    if (word==(a[i]))
        count++;
    }
  
    return count;
    }
    // Driver code
    let str = "GeeksforGeeks A computer
    science portal for geeks ";
    let word = "portal";
    document.write(countOccurrences(str, word));
     
     
    // This code is contributed by avanitrachhadiya2155
     
</script>

PHP

<?php 
// PHP program to count the number 
// of occurrence of a word in
// the given string
 
function countOccurrences($str, $word) 
{
    // split the string by spaces
    $a = explode(" ", $str);
 
    // search for pattern in string
    $count = 0;
    for ($i = 0; $i < sizeof($a); $i++) 
    {
         
    // if match found increase count
    if ($word == $a[$i])
        $count++;
    }
 
    return $count;
}
 
// Driver code
$str = "GeeksforGeeks A computer science portal for geeks ";
$word = "portal";
echo (countOccurrences($str, $word));
 
// This code is contributed
// by ChitraNayal
?>

Output

Time Complexity: O(n)
Auxiliary Space: O(n)

Method #2: Using Count() function in python:

First, we split the string by spaces and store in list.
We use count() to find count of that word in list.

Below is the implementation:

C++

// C++ program to count the number of occurrence
// of a word in the given string
#include <bits/stdc++.h>
using namespace std;
 
int countOccurrences(string str, string word)
{
    // Split the string into words
    stringstream ss(str);
    string token;
    vector<string> wordslist;
 
    while (ss >> token) {
        wordslist.push_back(token);
    }
 
    // Count the number of occurrences of the given word
    int count = 0;
    for (int i = 0; i < wordslist.size(); i++) {
        if (wordslist[i] == word) {
            count++;
        }
    }
 
    return count;
}
 
// Driver code
int main()
{
    string str = "GeeksforGeeks A computer science portal "
                 "for geeks";
    string word = "portal";
    cout << countOccurrences(str, word);
    return 0;
}

Java

import java.util.*;
 
public class Main 
{
 
  // Function to count the number of occurrences of a word
  // in the given string
  static int countOccurrences(String str, String word)
  {
 
    // Splitting the string into words
    List<String> wordslist
      = Arrays.asList(str.split("\\s+"));
 
    // Counting the frequency of the given word
    return Collections.frequency(wordslist, word);
  }
 
  public static void main(String[] args)
  {
    // Input string
    String str
      = "GeeksforGeeks A computer science portal for geeks  ";
 
    // Word to be counted
    String word = "portal";
 
    // Printing the count of occurrences of the given
    // word in the input string
    System.out.println(countOccurrences(str, word));
  }
}

Python3

# Python program to count the number of occurrence
# of a word in the given string
def countOccurrences(str, word):
 
    wordslist = list(str.split())
    return wordslist.count(word)
 
 
# Driver code
str = "GeeksforGeeks A computer science portal for geeks  "
word = "portal"
print(countOccurrences(str, word))
 
# This code is contributed by vikkycirus

C#

using System;
using System.Collections.Generic;
 
public class GFG{
    // Function to count the number of occurrences of a word
    // in the given string
    static int CountOccurrences(string str, string word){
        // Splitting the string into words
        List<string> wordsList = new List<string>(str.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries));
 
        // Counting the frequency of the given word
        return wordsList.FindAll(w => w == word).Count;
    }
 
    public static void Main(string[] args){
        // Input string
        string str = "GeeksforGeeks A computer science portal for geeks  ";
 
        // Word to be counted
        string word = "portal";
 
        // Printing the count of occurrences of the given
        // word in the input string
        Console.WriteLine(CountOccurrences(str, word));
    }
}

Javascript

// Javascript program to count the number of occurrence
// of a word in the given string
function countOccurrences(str, word) {
  // Split the string into words
  let wordslist = str.split(" ");
 
  // Count the number of occurrences of the given word
  let count = 0;
  for (let i = 0; i < wordslist.length; i++) {
    if (wordslist[i] === word) {
      count++;
    }
  }
 
  return count;
}
 
// Driver code to test above functions
let str = "GeeksforGeeks A computer science portal for geeks";
let word = "portal";
console.log(countOccurrences(str, word));
// THIS CODE IS CONTRIBUTED BY KANCHAN AGARWAL

Output

Time Complexity: O(n)
Auxiliary Space: O(n)

Reference: split function python

METHOD 3:Using re.findall module in python.

APPROACH:

The above code uses the re module to find all non-overlapping occurrences of the given word in the given string, and returns the count of those occurrences.

ALGORITHM:

1.Use the re.findall() method to find all non-overlapping occurrences of the given word in the given string.
2.Return the length of the resulting list of occurrences.

C++

#include <iostream>
#include <string>
#include <regex>
 
using namespace std;
 
int count_word_occurrences2(const string& str, const string& word) {
    // Use regular expression to find all occurrences of the word in the string
    regex regex_word(word);
    sregex_iterator it(str.begin(), str.end(), regex_word);
    sregex_iterator end;
 
    // Calculate the count of occurrences
    int count = 0;
    while (it != end) {
        count++;
        ++it;
    }
 
    return count;
}
 
int main() {
    string str = "GeeksforGeeks A computer science portal for geeks";
    string word = "portal";
    int count = count_word_occurrences2(str, word);
    cout << "Occurrences of Word = " << count << " Time" << endl;
 
    return 0;
}

Java

import java.util.regex.*;
 
public class WordOccurrences {
    public static int countWordOccurrences(String str, String word) {
        // Use regular expression to find all occurrences of the word in the string
        Pattern pattern = Pattern.compile("\\b" + Pattern.quote(word) + "\\b");
        Matcher matcher = pattern.matcher(str);
 
        // Calculate the count of occurrences
        int count = 0;
        while (matcher.find()) {
            count++;
        }
 
        return count;
    }
 
    public static void main(String[] args) {
        String str = "GeeksforGeeks A computer science portal for geeks";
        String word = "portal";
        int count = countWordOccurrences(str, word);
        System.out.println("Occurrences of Word = " + count + " Time");
    }
}

Python3

import re
 
def count_word_occurrences2(string, word):
    return len(re.findall(word, string))
 
# Example usage:
string = "GeeksforGeeks A computer science portal for geeks"
word = "portal"
count = count_word_occurrences2(string, word)
print(f"Occurrences of Word = {count} Time")  # Output: Occurrences of Word = 1 Time

C#

using System;
using System.Text.RegularExpressions;
 
class Program
{
    static int CountWordOccurrences(string input, string word)
    {
        // Use regular expression to find all occurrences of the word in the input string
        Regex regex = new Regex(word);
        MatchCollection matches = regex.Matches(input);
 
        // Calculate the count of occurrences
        int count = matches.Count;
 
        return count;
    }
 
    static void Main(string[] args)
    {
        string input = "GeeksforGeeks A computer science portal for geeks";
        string word = "portal";
        int count = CountWordOccurrences(input, word);
        Console.WriteLine("Occurrences of Word = " + count + " Time");
    }
}

Javascript

// Function to count occurrences of a word in a string
function count_word_occurrences2(string, word) {
    // Use regular expression to find all occurrences of the word in the string
    const regex = new RegExp(word, 'g');
    const matches = string.match(regex);
 
    // Return the count of occurrences
    return matches ? matches.length : 0;
}
 
// Example usage:
const string = "GeeksforGeeks A computer science portal for geeks";
const word = "portal";
const count = count_word_occurrences2(string, word);
console.log(`Occurrences of Word = ${count} Time`);  // Output: Occurrences of Word = 1 Time

Output

Occurrences of Word = 1 Time

Time complexity: O(n),where n is the length of the string.

Space complexity: O(m), where m is the number of occurrences of the word in the string.

ajay0007

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Count words present in a string

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