Concatenate Meaning

In formal English, the term Concatenate is defined as an operation to join or link something together. The same concept is taken to define the operation of concatenation in computer programming. Computer programmers commonly use concatenation for joining end-to-end character strings.

For example, the concatenation of "Hello" + "World" will fetch you the output as "HelloWorld". In many programming languages, string concatenation has its own pre-defined function such as concat(), join(), etc., or the coders can concatenate two or more strings in the program using the '+' (plus) operator.

Note: If you are concatenating a variable of non-string type with a string, you first need to cast that variable into a string.

In this tutorial we will discover how Concatenation is done in different programming languages with the help of examples.

Concatenate in C

1. Using Loops

The first method to concatenate two strings in C is by loops.

Program

#include <stdio.h> 
int main() 
{  
 char str1[50] = "Concatenate ", str2[] = "in C programming";   
int len1, len2;    // holding the length of str1 in the integer variable named len1   
len1 = 0;   //initializing len1 with 0
while (str1[len1] != '\0') 
{     
++len1;   
}    // concatenate str2 to str1   
for (len2 = 0; str2[len2] != '\0'; ++len2, ++len1) 
{     
str1[len1] = str2[len2];   
}   
 // terminating the str1 string   
str1[len1] = '\0';    
printf("After concatenation: ");   
puts(str1);    
return 0; 
}

Output:

After concatenation: Concatenate in C programming

Explanation:

In the above example, we have taken two strings and have named them str1 and str2 respectively. Have applied while and for loop to concatenate both the strings and later have stored the result in str1.

NOTE: Please make sure that the length of str1 should be sufficient to store the output after concatenating the string. If the length is short, the C compiler may throw some expected error.

2. Using strcat()

In C programming, there is an inbuilt function strcat(), used to concatenate two string values.

Syntax

Parameter

String1: This parameter represents the first string to which the following string will be concatenated.
String2: This represents the second string that you wish to add with string1.

Program

#include <stdio.h>  
#include<string.h>  
int main()  
{  
  char str1[100]; // declaring the first array character  
  char str2[100]; // declaring the second array character    
printf("Enter your first string : ");  
scanf("%s", str1);  
printf("\n Enter your next string :");  
scanf("%s",str2);  
//concatenating both the strings using strcat() function
strcat(str1,str2);  
printf("Result after concatenating both the strings is : %s",str1);  
    return 0;  
} 

Output:

Enter the first number: 34

Enter the second number: 23

The output after concatenation: 3423

Example:

In the above program, we have used the inbuilt strcat() function to concatenate two strings. As you can see, it has taken two strings, i.e., str1 and str2, as its parameters, and then appends the str2 at the end of the str1 (first string).

Concatenate in C++

In C++, you can concatenate two strings together using + (string concatenation) operator or by append() function.

1. By '+' (string concatenation) operator

In C++, the programmers can leverage the advantage of the '+' operator to append two strings together to create a new string. This process is known as concatenation.

Example

#include <iostream>
#include <string>
using namespace std;
 
int main () {
  string firstNameClient = "Hello ";//declaring the first string
    string lastNameClient = "World";// declaring the second string
  
  //using the '+' operator to concatenate first string and second string
    string fullNameClient = firstNameClient + lastNameClient;

    //printing the output stored in third string
    cout << fullNameClient;
    return 0;
}

Output:

2. C++ Append() function

A string in C++ is actually an object, which contains functions that can perform certain operations on strings. For example, you can also concatenate strings with the append() function:

Syntax

Parameters

String1: This parameter represents the first string to which the following string will be concatenated.
String2: This represents the second string that you wish to add with string1.

Example:

#include <iostream>
#include <string>
using namespace std;
 
int main () {

  string firstNameClient = "Hello ";//declaring the first string
    string lastNameClient = "World";// declaring the second string
    
//using the append() function to concatenate first string and second string
    string fullNameClient = firstNameClient.append (lastNameClient);

//printing the output stored in third string
    cout << fullNameClient;
    return 0;
  }

Output:

Concatenate in Java

In java, you can concatenate two different strings together using concat() function and also the same string to itself multiple times using + operator or respectively.

1. By + (string concatenation) operator

Java concatenation operator (+) is used to combine two string values to create one new string.

Example

JavaStringConcatenate.java

class JavaConcatenateExample{  
    
 public static void main(String args[]){ 

    //using the '+' operator to concatenate two string
   String str="Hello"+" World"; 
   
//it will return the output as Helloworld
   System.out.println(str);
 }  
}

Output:

2. Java concat() method

The concat() method in Java appends the given second string to the end of the first string and stores it to a new string.

Syntax:

Parameters

str1 (required): This parameter represents the first string.
str2 (required): This parameter represents the second string that is concatenated to the end of the first string.

Example

class JavaConcatenateExample{  
public static void main(String args[]){ 
  // declaring the first string
   String str1="Hello ";  
  // declaring the second string
   String str2="World";  
  //concatenating string 1 and string 2 using concat() function
   String str3=str1.concat(str2); 
  //it will return Hello World
   System.out.println(str3);
  }  
}

Output:

Concatenation in PHP

1. '.' Operator

PHP string concatenation operator (.) adds two strings.

Example

<?php     
$firstName="Reema";     
$lastName="Panda";
//concatenating both the string using PHP '.' operator
echo $firstName." ".$lastName; // Outputs Reema Panda      
?>

Output:

Reema Panda

2. '.=' Operator

The PHP Concatenation assignment represented by '.=' operator is used to combine two strings.

Example

<?php     
//declaring the first string
$str1="Hello"; 
//declaring the second string
$str2=" World!"; 

//concatenating the first and second string using .= operator
$str1 .= $str2;     

// Outputs Hello World! 
echo $str1; 
?>

Output:

Hello World!

Concatenation in Python

1. Use the + (string concatenation) operator

The Python '+' (string concatenate) operator is used to combine two different strings together.

Example

#declaring the first string
firstName="Reema "
#declaring the second string
lastName="Panda"
print ("First Name:",firstName)
print ("Last String:",lastName)
#concatenating the string using '+' (string concatenate) operator
fullName=firstName+lastName
print("\nAfter Concatenating the strings......\n")
print ("Full Name:",fullName)

Output:

2. Using join() method

The Python join() is a string method that concatenates the string with the elements of iterable.

Syntax

Parameters

strName: This represents the name of a string where the elements of iterable will be stored.

iterable: This parameter represents the objects that are capable of returning its elements one at a time. It could be List, Tuple, String, Set, etc.,

Return

The join() method in Python returns the concatenated string.

Example:

# Python program to illustrate the concatenate example
# use of join() method .
  
set_Val= ['R','E','E','M','A'] 
  
strName = " "
  
# concatenating the elements of setVal by a space' '
# and storing the output in strName 
strName = strName.join(set_Val)
  
# printing the result
print(set_Val)

Output:

Concatenate in C#

1. Using '+' operator

In C# two strings can be concatenated using the '+' operator.

Example

// C# program to demonstrate concatenation
// by using '+' operator'
  
using System;
public class OperatorConcatenateExample {
      
    static public void Main()
    {
        string str1 = "Hello ";//declaring the first string
        string str2 = "World!";//declaring the second string
        string str3;
  
        // print all strings
        Console.WriteLine("String First: {0}", str1);
        Console.WriteLine("String second: {0}", str2);
  
        // concatenating str1 and str2 using '+' operator
        // storing the output in str
         str3 = str1+ str2;
  
        Console.WriteLine("The result after Concatenation: {0}", str3);
    }
}

Output:

2. Using the String.Concat Method

The String.Concat method in C# concatenates one or more instances of String and returns a concatenated string.

Syntax

Parameters

str1 (required): This parameter represents the first string to concatenate.

str2 (required): It represents the second string to concatenate.

Return

This method returns a concatenated string.

Example:

// C# program to demonstrate concatenate example
// using Concat(str1, str2) method
using System;
  
public class ConcatExample {
      
    static public void Main()
    {
        string str1 = "Hello"; //Declaring the first string
        string str2 = " World!"; // Declaring the second string
        string str3;
  
        //pritning the values of the string
        Console.WriteLine("The first String: {0}", str1);
        Console.WriteLine("The second string: {0}", str2);
  
        // Concatenating str1 and str2
        // using C# concat method
        // and storing the values in str3
        str3 = String.Concat(str1, str2);
  
        Console.WriteLine("The result after Concatenation: {0}", str3);
    }
}

Output: