Concatenating Strings (combining multiple strings into one)

Last Updated : 17 Nov, 2023

Given two strings str1 and str2, the task is to concatenate these two strings.

Examples:

Input: str1 = "hello", str2 = "world"
Output: helloworld

Input: str1 = "Geeks", str2 = "World"
Output: GeeksWorld

Approach 1: Using the "+" operator

The most traditional method of concatenating strings is by using the "+" operator.

Below is the implementation of the above method:

C++

#include <iostream>
#include <string>

using namespace std;

int main()
{
    string str1 = "Geeks";
    string str2 = "ForGeeks";
    string result = str1 + str2;
    cout << result << endl;
    return 0;
}

Java

// Java program to Illustrate Working of concat() method
// with Strings

// Main class
class GFG {
    // Main driver method
    public static void main(String args[])
    {
        // Custom input string 1
        String s1 = "Geeks";

        // Custom input string 2
        String s2 = "forGeeks");

        String result = s1 + s2;

        // Print and display combined string
        System.out.println(result);
    }
}

Python3

# Defining strings
str1 = "Hello "
str2 = "Geek"

# + Operator is used to combine strings
str3 = str1 + str2
print(str3)

// C# program to Illustrate Working of concat() method
// with Strings
using System;

// Main class GFG
class GFG
{
      // Main driver method
    public static void Main(string[] args)
    {
          // Custom input string 1
        string s1 = "Geeks";
      
          // Custom input string 2
        string s2 = "forGeeks";
        string result = s1 + s2;
      
          // Print and display combined string
        Console.WriteLine(result);
    }
}

JavaScript

// Define the main function
function main() {
    // Declare and initialize strings
    let str1 = "Geeks";
    let str2 = "ForGeeks";
    
    // Concatenate the two strings
    let result = str1 + str2;
    
    // Print the concatenated result
    console.log(result);
}

// Call the main function
main();

// This Code Is Contributed By Shubham Tiwari

Output

GeeksForGeeks

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

Approach 2: Using In-built methods

Every programming language offers a built-in method as well to concatenate strings, such as:

Programming Language	In-Built method to find length of string
C	strcat()
C++	append( )
Java	concat()
JavaScript	concat()
Python	join()

Below is the implementation of the above method:

C++

// C++ Program for string
// concatenation using append
#include <iostream>
using namespace std;

// Driver code
int main()
{
    string s = "Geeks";
    string s1 = "forGeeks";

    // Appending the string.
    s.append(s1);

    cout << s << endl;
    return 0;
}

// C program to concatenate two
// strings using strcat function
#include <stdio.h>
#include <string.h>

int main()
{

    char s[] = "Geeks";
    char s1[] = "forGeeks";

    // concatenating the string
    strcat(s, s1);
    printf(s);
    return 0;
}

Java

// Java program to Illustrate Working of concat() method
// with Strings

// Main class
class GFG {
    // Main driver method
    public static void main(String args[])
    {
        // Custom input string 1
        String s = "Geeks";
        String s1 = "forGeeks";

        // Custom input string 2
        s = s.concat(s1);

        // Explicitly assigning result by
        // Combining(adding, concatenating strings)
        // using concat() method

        // Print and display combined string
        System.out.println(s);
    }
}

Python3

s = "Geeks"
s1 = "forGeeks"

# join() method is used to combine the strings
print("".join([s, s1]))

# join() method is used here to combine
# the string with a separator Space(" ")
# s = " ".join([s, s1])

# print(s)

using System;

class Program {
    static void Main() {
        string s = "Geeks";
        string s1 = "forGeeks";

        // Concatenating the strings.
        s = string.Concat(s, s1);

        Console.WriteLine(s);
    }
}

JavaScript

// JavaScript code for the above approach

// Function to concatenate strings using the 'concat' method
function concatenateStrings() {
    let s = "Geeks";
    let s1 = "forGeeks";

    // Appending the strings
    s = s.concat(s1);

    console.log(s);
}

// Driver code
concatenateStrings();

// This code is contributed by Abhinav Mahajan (abhinav_m22)