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How to concatenate two Integer values into one?

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Given two integers n1 and n2, the task is to concatenate these two integers into one integer.
Example: 
 

Input: n1 = 12, n2 = 34
Output: 1234

Input: n1 = 1, n2 = 93
Output: 193

 

Approach: The simplest approach to do this is: 
 

  • Convert both numbers to string
  • Concatenate both strings into one, as this is comparatively easy
  • Convert this concatenated string back to integer

Program:
 

C++




// CPP program to concatenate
// two integers into one
  
#include <iostream>
#include <string>
using namespace std;
  
// Function to concatenate
// two integers into one
int concat(int a, int b)
{
  
    // Convert both the integers to string
    string s1 = to_string(a);
    string s2 = to_string(b);
  
    // Concatenate both strings
    string s = s1 + s2;
  
    // Convert the concatenated string
    // to integer
    int c = stoi(s);
  
    // return the formed integer
    return c;
}
  
int main()
{
    int a = 23;
    int b = 43;
  
    cout << concat(a, b) << endl;
  
    return 0;
}
  
// This code is contributed by Ayush Singla(@ayusin51)


C




// C program to concatenate
// two integers into one
  
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
  
// Function to concatenate
// two integers into one
int concat(int a, int b)
{
  
    char s1[20];
    char s2[20];
  
    // Convert both the integers to string
    sprintf(s1, "%d", a);
    sprintf(s2, "%d", b);
  
    // Concatenate both strings
    strcat(s1, s2);
  
    // Convert the concatenated string
    // to integer
    int c = atoi(s1);
  
    // return the formed integer
    return c;
}
  
int main()
{
    int a = 23;
    int b = 43;
  
    printf("%d\n", concat(a, b));
  
    return 0;
}
  
// This code is contributed by Ayush Singla(@ayusin51)


Java




// Java program to concatenate
// two integers into one
  
public class GFG {
  
    // Function to concatenate
    // two integers into one
    static int concat(int a, int b)
    {
  
        // Convert both the integers to string
        String s1 = Integer.toString(a);
        String s2 = Integer.toString(b);
  
        // Concatenate both strings
        String s = s1 + s2;
  
        // Convert the concatenated string
        // to integer
        int c = Integer.parseInt(s);
  
        // return the formed integer
        return c;
    }
  
    public static void main(String args[])
    {
        int a = 23;
        int b = 43;
  
        System.out.println(concat(a, b));
    }
}


Python3




# Python3 program to concatenate
# two integers into one
  
# Function to concatenate
# two integers into one
def concat(a, b):
      
    # Convert both the integers to string
    s1 = str(a)
    s2 = str(b)
      
    # Concatenate both strings    
    s = s1 + s2
      
    # Convert the concatenated string
    # to integer
    c = int(s)
      
    # return the formed integer
    return c
  
# Driver code
  
a = 23
b = 43
  
print(concat(a, b))
  
# This code is contributed by shubhamsingh10


C#




// C# program to concatenate
// two integers into one
using System;
  
class GFG
{
  
    // Function to concatenate
    // two integers into one
    static int concat(int a, int b)
    {
  
        // Convert both the integers to string
        String s1 = a.ToString();
        String s2 = b.ToString();
  
        // Concatenate both strings
        String s = s1 + s2;
  
        // Convert the concatenated string
        // to integer
        int c = int.Parse(s);
  
        // return the formed integer
        return c;
    }
  
    // Driver code
    public static void Main(String []args)
    {
        int a = 23;
        int b = 43;
  
        Console.WriteLine(concat(a, b));
    }
}
  
/* This code contributed by PrinciRaj1992 */


Javascript




<script>
  
// JavaScript program to concatenate
// two integers into one
  
  
    // Function to concatenate
    // two integers into one
    function concat(a , b) {
  
        // Convert both the integers to string
        var s1 = a.toString();
        var s2 = b.toString();
  
        // Concatenate both strings
        var s = s1 + s2;
  
        // Convert the concatenated string
        // to integer
        var c = parseInt(s);
  
        // return the formed integer
        return c;
    }
  
      
        var a = 23;
        var b = 43;
  
        document.write(concat(a, b));
  
// This code contributed by Rajput-Ji
  
</script>


Output: 

2343

Time Complexity: O(d1+d2) where d1=log10(a) and d2=log10(b)

Auxiliary Space: O(d1+d2)
 



Last Updated : 13 Dec, 2023
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