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Check if two numbers are equal without using comparison operators

Last Updated : 19 Dec, 2022
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The following are not allowed to use 

  1. Comparison Operators 
  2. String function

Examples:  

Input : num1 = 1233, num2 =1233
Output : Same

Input : num1 = 223, num2 = 233
Output : Not Same

Method 1: The idea is to use the XOR operator. XOR of two numbers is 0 if the numbers are the same, otherwise non-zero. 

C++ 
#include <iostream>
using namespace std;
 
// Finds if a and b are same.
void areSame(int a, int b)
{
   if (a^b) 
       cout << "Not Same"; 
   else 
       cout << "Same";
}
 
int main()
{  
   areSame(10, 20);
}
Java 
class GFG
{
    // Finds if a and b are same
    static void areSame(int a,int b)
    {
        if( (a ^ b) != 0 )
            System.out.println("Not Same");
        else
            System.out.println("Same");
    }

    public static void main(String args[])
    {
        areSame(10,20);
    }
    
}
// This code is contributed by Sumit Ghosh
Python3 
# Finds if a and b are same.
def areSame(a, b):
   if (a ^ b): 
       print("Not Same")
   else:
       print("Same")
  
# Driver code
areSame(10, 20)

# This code is submitted by Sachin Bisht
C# 
// C# program to check if 2 
// numbers are same
using System;

class GFG
{
    // Finds if a and b are same
    static void areSame(int a, int b)
    {
        if( (a ^ b) != 0 )
          Console.Write("Not Same");
        else
          Console.Write("Same");
    }
   
    // Driver code
    public static void Main()
    {
               
        // Calling Function
        areSame(10, 20);
    }
    
}

// This code is contributed by Nitin Mittal.
PHP 
<?php

// Finds if a and b are same.
function areSame($a, $b)
{
    if ($a ^ $b) 
        echo "Not Same"; 
    else
        echo "Same";
}

// Driver Code
areSame(10, 20);

// This code is contributed by nitin mittal
?>
JavaScript 
<script>

// Finds if a and b are same. 

function areSame(a, b) 
{ 
if (a^b) 
    document.write("Not Same"); 
else
    document.write("Same"); 
} 

// Driver code 
areSame(10, 20); 

// This code is contributed by Surbhi Tyagi.

</script>

Output
Not Same

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

Method 2: We can subtract the numbers. The same numbers yield 0. If the answer is not 0, the numbers are not the same. 

C++ 
// CPP code to check if 2 numbers are same
#include <bits/stdc++.h>
using namespace std;

// Finds if a and b are same
void areSame(int a, int b)
{
    if (!(a - b))
        cout << "Same";
    else
        cout << "Not Same";
}

// Driver code
int main() 
{    
     areSame(10, 20);    
    return 0;
}
Java 
// Java code to check if 2 numbers are same
class GFG{ 

    // Finds if a and b are same
    static void areSame(int a, int b)
    {
        if ((a - b) == 0)
            System.out.println("Same");
        else
            System.out.println("Not Same");
    }
 
    // Driver code
    public static void main(String args[]) 
    {    
        areSame(10, 20);    
    
    }
}
//This code is contributed by Sumit Ghosh
Python3 
# Python code to check if 2 numbers are same

# Finds if a and b are same
def areSame(a, b):
    if (not(a - b)):
        print ("Same")
    else:
        print ("Not Same")
# Driver code
areSame(10, 20)

# This code is submitted by Sachin Bisht
C# 
// C# code to check if 2 
// numbers are same
using System;

class GFG
{ 

    // Finds if a and b are same
    static void areSame(int a, int b)
    {
        if ((a - b) == 0)
            Console.Write("Same");
        else
            Console.Write("Not Same");
    }

    // Driver code
    public static void Main() 
    { 
        
        // Calling Function
        areSame(10, 20); 
    }
}

// This code is contributed by Nitin Mittal.
PHP 
<?php
// PHP code to check if 2 
// numbers are same

// Finds if a and b are same
function areSame($a, $b)
{
    if (!($a - $b))
        echo "Same";
    else
        echo "Not Same";
}

// Driver code
areSame(10, 20); 

// This code is contributed by nitin mittal
?>
JavaScript 
<script>
// javascript code to check if 2 numbers are same
 

// Finds if a and b are same
function areSame(a , b)
{
    if ((a - b) == 0)
        document.write("Same");
    else
        document.write("Not Same");
    }
 
    // Driver code
areSame(10, 20); 

// This code contributed by Princi Singh 
</script>

Output
Not Same

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

Method 3: The bitwise AND of one number and the complement of the other number is zero if they are the same, and non-zero if they are not the same.

Below is the implementation of the above approach:

C++ 
#include <iostream>
using namespace std;

// Finds if a and b are same.
void areSame(int a, int b)
{
    if (a & (~b))
        cout << "Not Same" << endl;
    else
        cout << "Same" << endl;
}

// Driver code
int main()
{
    areSame(10, 20);
}

// This code is contributed by phasing17
Java 
import java.io.*;

class GFG {
    // Finds if a and b are same.
static void areSame(int a, int b)
{
    if ((a & (~b)) != 0 )
        System.out.println("Not Same");
    else
        System.out.println("Same");
}
// Driver code
    public static void main (String[] args) {
        areSame(10, 20);
    }
}

// This code is contributed by Pushpesh Raj.
Python3 
# Python code to check if 2 numbers are same

# Finds if a and b are same
def areSame(a, b):
    if (a & ~b):
        print ("Not Same")
    else:
        print ("Same")
# Driver code
areSame(10, 10)
areSame(10, 20)

# This code is contributed by phasing17
C# 
// C# program to find min operation to convert a to b
using System;

class GFG
{

  // Finds if a and b are same.
  static void areSame(int a, int b)
  {
    if (Convert.ToBoolean(a & (~b)))
      Console.WriteLine("Not Same");
    else
      Console.WriteLine("Same");
  }

  // Driver code
  public static void Main(string[] args)
  {
    areSame(10, 20);
  }
}

// This code is contributed by phasing17
JavaScript 
//JavaScript code to implement the approach

// Finds if a and b are same.
function areSame(a, b)
{
    if (a & (~b))
        console.log("Not Same");
    else
        console.log("Same");
}

// Driver code
areSame(10, 20);


// This code is contributed by phasing17

Output
Not Same

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


 


R

Rohit Thapliyal
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