URLify a given string (Replace spaces with %20)

Last Updated : 24 Apr, 2025

Given a string s, the task is to replace all the spaces in the string with '%20'.

Examples:

Input: s = "i love programming"
Output: "i%20love%20programming"
Explanation: The 2 spaces are replaced by '%20'
Input: s = "ab cd"
Output: "ab%20cd"

Approach:

The idea is to iterate through each character of the input string and create a new string by replacing space characters with the '%20' escape sequence.

Step by step approach:

Iterate through each character in the input string from start to end.
Check if the current character is a space.
- If a space is found, append '%20' to the result string.
- If the current character is not a space, append the original character to the result string.
Return the final modified string with spaces replaced by '%20'.

C++

// C++ program to URLify a given string
#include <bits/stdc++.h>
using namespace std;

string URLify(string& s) {
    int n = s.length();
	
	string ans = "";
	for (int i = 0; i<n; i++) {
	    
	    // If " " is encountered, 
	    // append "%20" to string
		if (s[i] == ' ') {
		    ans += "%20";
		}
		
		// Else append the current 
		// character.
		else {
		    ans += s[i];
		}
	}

	return ans;
}

int main() {
	string s = "i love programming";
	cout << URLify(s);
	return 0;
}

Java

// Java program to URLify a given string

class GfG {

    static String URLify(String s) {
        int n = s.length();
        
        StringBuilder ans = new StringBuilder();
        for (int i = 0; i < n; i++) {
            
            // If " " is encountered, 
            // append "%20" to string
            if (s.charAt(i) == ' ') {
                ans.append("%20");
            }
            
            // Else append the current 
            // character.
            else {
                ans.append(s.charAt(i));
            }
        }

        return ans.toString();
    }

    public static void main(String[] args) {
        String s = "i love programming";
        System.out.println(URLify(s));
    }
}

Python

# Python program to URLify a given string

def URLify(s):
    n = len(s)
    
    ans = ""
    for i in range(n):
        
        # If " " is encountered, 
        # append "%20" to string
        if s[i] == ' ':
            ans += "%20"
        
        # Else append the current 
        # character.
        else:
            ans += s[i]
    
    return ans

if __name__ == "__main__":
    s = "i love programming"
    print(URLify(s))

// C# program to URLify a given string
using System.Text;
using System;

class GfG {

    static string URLify(string s) {
        int n = s.Length;
        
        StringBuilder ans = new StringBuilder();
        for (int i = 0; i < n; i++) {
            
            // If " " is encountered, 
            // append "%20" to string
            if (s[i] == ' ') {
                ans.Append("%20");
            }
            
            // Else append the current 
            // character.
            else {
                ans.Append(s[i]);
            }
        }

        return ans.ToString();
    }

    static void Main() {
        string s = "i love programming";
        Console.WriteLine(URLify(s));
    }
}

JavaScript

// JavaScript program to URLify a given string

function URLify(s) {
    let n = s.length;
    
    let ans = "";
    for (let i = 0; i < n; i++) {
        
        // If " " is encountered, 
        // append "%20" to string
        if (s[i] === ' ') {
            ans += "%20";
        }
        
        // Else append the current 
        // character.
        else {
            ans += s[i];
        }
    }

    return ans;
}

let s = "i love programming";
console.log(URLify(s));

Output

i%20love%20programming

Time Complexity: O(n), as the string is traversed only once.
Auxiliary Space: O(n), used for output string.

Count of total anagram substrings

Aarti_Rathi and Brahmani Sai

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URLify a given string (Replace spaces with %20)

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