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:

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

Auxiliary Space: O(d1+d2)

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