Program to check if two strings are same or not

Given two strings, the task is to check if these two strings are identical(same) or not. 

Examples:

Input: string1 = “GeeksforGeeks”, string2 = “GeeksforGeeks” 
Output: Yes 

Input: string1 = “Geeks for Geeks”, string2 = “Geeks for Geeks” 
Output: Yes 

Input: string1 = “GeeksforGeeks”, string2 = “Geeks” 
Output: No 

Input: string1 = “Geeks for Geeks”, string2 = “Geeks for geeks” 
Output: No

Brute Force Way:

     The Approach:

Using (==) Operator in C++/Java and using (is) operator in Python.

C++

#include <iostream>
#include<string>
#include<bits/stdc++.h>
using namespace std;

int main() {
    // first string.
    string s1 = "GeeksforGeeks";
    // second string.
    string s2 = "Geeks for geeks";
    // check condition.
    if(s1==s2){
      cout<<"Strings Are Equal"<<endl;
    }else{
      cout<<"Strings Are Not Equal"<<endl;
    }
    return 0;
}

Java

import java.util.*;

public class Main {
    public static void main(String[] args) {
        // first string
        String s1 = "GeeksforGeeks";
        // second string
        String s2 = "Geeks for geeks";
        // check condition
        if (s1.equals(s2)) {
            System.out.println("Strings Are Equal");
        } else {
            System.out.println("Strings Are Not Equal");
        }
    }
}
// This code is contributed by divyansh2212

Python3

# Python3 program to check 2 strings are identical or not

if __name__ == "__main__":

  #first string.
  string1 = "GeeksforGeeks"
  #second string.
  string2 = "Geeks for geeks"

  #check condition
  if (string1 is string2):
    print("Strings Are Equal")
  else:
    print("Strings Are Not Equal")


  # This Code is contributed by Pratik Gupta

Javascript

// js code implementation

const s1 = "GeeksforGeeks";
const s2 = "Geeks for geeks";

if (s1 === s2) {
    console.log("Strings Are Equal");
} else {
    console.log("Strings Are Not Equal");
}
// code by ksam24000

C#

using System;

class GFG
{
    static void Main(string[] args)
    {
        // first string
        string s1 = "GeeksforGeeks";
        // second string
        string s2 = "Geeks for geeks";
        // check condition
        if (s1 == s2)
        {
            Console.WriteLine("Strings Are Equal");
        }
        else
        {
            Console.WriteLine("Strings Are Not Equal");
        }
    }
}
// code by ksam24000

Output

Strings Are Not Equal

Complexity Analysis:

Time Complexity: O(1).
Auxiliary Space: O(1).

Approach 1:

This can be done with the help of strcmp() method in C. Please note, this method is case-sensitive. 

Implementation:

C

// C program to check if
// two strings are identical

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

int main()
{

    char string1[100], string2[100];

    // Get the strings which
    // is to be checked
    scanf("%[^\n]\ns", string1);
    printf("Enter the first string: %s", string1);

    // Get the strings which
    // is to be checked
    scanf("%[^\n]\ns", string2);
    printf("\nEnter the second string: %s", string2);

    // Check if both strings are equal
    printf("\nAre both strings same: ");

    if (strcmp(string1, string2) == 0) {
        printf("Yes");
    }
    else {
        printf("No");
    }

    return 0;
}

C++

// C++ program to check if
// two strings are identical
#include <bits/stdc++.h>
using namespace std;

int main()
{

    char string1[100], string2[100];

    // Get the strings which
    // is to be checked
    cin >> string1;
    cout << "Enter the first string: " << string1;

    // Get the strings which
    // is to be checked
    cin >> string2;
    cout << "\nEnter the second string: " << string2;

    // Check if both strings are equal
    cout << "\nAre both strings same: ";

    if (strcmp(string1, string2) == 0) {
        cout << "Yes";
    }
    else {
        cout << "No";
    }

    return 0;
}

// This code is contributed by Akanksha Rai

Java

// Java program to check if
// two strings are identical
import java.util.*;

class GFG {

    // Driver code
    public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);

        // Get the strings which is to be checked
        String string1 = in.nextLine();
        System.out.println("Enter the first string: "
                           + string1);

        // Get the strings which is to be checked
        String string2 = in.nextLine();
        System.out.println("Enter the second string :"
                           + string2);

        // Check if both strings are equal
        System.out.println("\nAre both strings same: ");

        if (string1.equals(string2) == true) {
            System.out.println("Yes");
        }
        else {
            System.out.println("No");
        }
    }
}

// This code is contributed by aishwarya.27

Python 3

# Python program to check if
# two strings are identical

if __name__ == "__main__":

    # Get the strings which
    # is to be checked
    string1 = input("Enter the first string: ")
    print(string1, end="\n")

    # Get the strings which
    # is to be checked
    string2 = input("Enter the second string: ")
    print(string2, end="\n")

    # Check if both strings are equal
    print("Are both strings same: ", end=" ")

    if (string1 == string2):
        print("Yes")

    else:
        print("No")

# This code is contributed by Ryuga

C#

// C# program to check if
// two strings are identical
using System;

class GFG {

    // Driver code
    public static void Main()
    {

        // Get the strings which is to be checked
        String string1 = Console.ReadLine();
        Console.WriteLine("Enter the first string: "
                          + string1);

        // Get the strings which is to be checked
        String string2 = Console.ReadLine();
        Console.WriteLine("Enter the second string :"
                          + string2);

        // Check if both strings are equal
        Console.WriteLine("\nAre both strings same: ");

        if (string1.Equals(string2) == true) {
            Console.WriteLine("Yes");
        }
        else {
            Console.WriteLine("No");
        }
    }
}

/* This code contributed by PrinciRaj1992 */

PHP

<?php
// PHP program to check if
// two strings are identical


// Get the strings which
// is to be checked
$string1 = readline();
echo "Enter the first string: $string1";

// Get the strings which
// is to be checked
$string2 = readline();
echo "\nEnter the second string: $string2";

// Check if both strings are equal
echo "\nAre both strings same: ";

if (strcmp($string1, $string2) == 0)
{
    echo "Yes";
}

else if (strcmp($string1, $string2) > 0) //Because string1 has some character greater than string2
{
    echo "No";
}

else if (strcmp($string1, $string2) < 0) //Because string2 has some character greater than string1
{
    echo "No";
}

// This code is contributed by Ashutosh Tiwari

?>

Output

Enter the first string: ��}��
Enter the second string: �`
Are both strings same: No

Time Complexity: O(min(a,b)) // a is the length of the first string and b is the length of the second string.
Auxiliary Space: O(100) 

Approach 2 : (Using two pointer approach)

The problem can be easily solved using two pointer approach. But before using two pointer one basic check that can be performed is the length. As it is very obvious to be same they will contain same length. If both of their length is same then we can perform the 2 pointer technique.

Output

Enter the first string: 
Enter the second string: 
Are both strings same: Yes

Time Complexity: O(N), for traversing using two pointers over the string in case their size is equal
Auxiliary Space: O(1), no extra space is used

Approach-3 : Using not equal to(!=) operator

Using the not equal to operator we can check whether both of the strings are equal or not.

C++

#include <iostream>
#include<string>
using namespace std;

int main() {
    // first string.
    string s1 = "GeeksforGeeks";
    // second string.
    string s2 = "Geeks for geeks";
    // check condition.
    if(s1!=s2){
      cout<<"Strings Are Not Equal"<<endl;
    }else{
      cout<<"Strings Are Equal"<<endl;
    }
    return 0;
}

Java

/*package whatever //do not write package name here */

import java.io.*;

public class Main {
    public static void main(String[] args)
    {
        // first string.
        String s1 = "GeeksforGeeks";
        // second string.
        String s2 = "Geeks for geeks";
        // check condition.
        if (!s1.equals(s2)) {
            System.out.println("Strings Are Not Equal");
        }
        else {
            System.out.println("Strings Are Equal");
        }
    }
}

Python3

# Python Program to check
# if two strings are same or not
# using != operator


def is_string_same(str1, str2):

    if str1 != str2:
        return 0
    else:
        return 1

# Driver Code


# First String
s1 = "GeeksforGeeks"

# Second String
s2 = "Geeks for geeks"

# Storing the Result
result = is_string_same(s1, s2)

# Checking the value stored in result
# if returned 0 then Strings are not same
# Else returned 1 then strings are same

if result == 0:
    print("Strings are Not Equal")
else:
    print("Strings are Equal")

Javascript

// first string
let s1 = "GeeksforGeeks";
// second string
let s2 = "Geeks for geeks";
// check condition
if (s1 !== s2) {
  console.log("Strings Are Not Equal");
} else {
  console.log("Strings Are Equal");
}

C#

using System;

class Gfg {
    static void Main(string[] args) {
        // first string.
        string s1 = "GeeksforGeeks";
        // second string.
        string s2 = "Geeks for geeks";
        // check condition.
        if (s1 != s2) {
            Console.WriteLine("Strings Are Not Equal");
        } else {
            Console.WriteLine("Strings Are Equal");
        }
    }
}

Output

Strings Are Not Equal

Complexity Analysis:

Time Complexity: O(1)
Auxiliary Space: O(1)