C# Concatenate Strings

6 Effective Ways To Concatenate Strings In C#

Here are six different ways to concatenate strings in C#.

1. Use of + operator
2. Use of String Interpolation
3. Use of String.Concatenate() method
4. Use of String.Join() method
5. Use of String.Format() method
6. Use of StringBuilder.Append() method

Now let’s discuss these methods one by one.

Also read - C program to concatenate two strings

C# Concatenate Strings Using + Operator

The + or += operators are the simplest way to add two strings in C#.

Example 1 shows a code example that concatenates two strings and a special character.

Example 1:

using System;

class Example1 {
  static void Main() {
    // Simple string concatenation
    Console.WriteLine("Hello" + " " + "String " + "!");
    
    // Declare strings
    string fName = "Coding";
    string lName = "Ninjas";
    
    // Concatenate two string variables
    string name = fName + " " + lName;
    Console.WriteLine(name);

  }
}

Output 1:

Concatenation occurs at compile time for string literals and string constants; no concatenation occurs at run time. Concatenation of string variables happens only at run time.

String Interpolation in C#

String interpolation is a technique for joining variables as part of a string. String interpolation syntax begins with a '$' symbol, and code variables are enclosed in brackets.

The following code example concatenates strings to form a longer string.

Example 2:

using System;

class Example2 {
  static void Main() {
    // String Interpolation
    string city= "Mumbai";
    string country = "India";
    
    // Use string interpolation to concatenate strings.
    string cityOfcountry = $"{city} is a city in {country}.";
    Console.WriteLine(cityOfcountry);
  }
}

Output 2:

String.Concatenate() in C#

String.Concate() is a method that adds two strings, objects, and arrays of strings and string combinations. Let us see hoe to use it with an example.

Example 3:

using System;

class Example3 {
  static void Main() {
    // String.Concat method
    string String1 = "Coding";
    string String2 = "Ninjas";
    string finalString = string.Concat(String1, String2);
    
    Console.WriteLine(finalString);
  }
}

Output 3:

We can also use the C# Concatenate String method “concat”, to add two concats together. The last line might seem intimidating initially, but it is easy to implement. Let us see how to do it.

Example 4:

using System;

class Example4{
  static void Main() {
    // String.Concat method
    string String1 = "Coding";
    string String2 = "Ninjas";
    
    string finalString = string.Concat(String1, String2);
    
    Console.WriteLine(finalString);
    
    // Concatenate Concat
    string doubleConcat = string.Concat(string.Concat(String1, String2), "Company"); 
    
    Console.WriteLine(doubleConcat);
  }
}

Output 4:

String.Join() in C#

String.Join() concatenates array elements or collection members using the specified separator between each of the elements or members. The array or collection can contain any data, including numbers and objects. String.Join() can also concatenate string items of any data type with a range.

Let us see an example.

Example 5:

using System;

class Example5{
  static void Main() {
    // Using String.Join(String, String[])
    int[] inputArray = { 89, 78, 34, 76, 34, 21 };
    String sep = "; ";
    string finalresult = "Int: ";
    
    finalresult += String.Join(sep, inputArray);
    Console.WriteLine($"Result: {finalresult}");
  }
}

Output 5:

String.Format() in C#

String.format() method formats strings by inserting objects and variables into other strings and literals with specified space and alignments. It is also frequently used to format strings into predefined formats.

String.Format() method has eight overloaded formats to provide options for formatting various objects and variables, including variables that can format strings. The eight overloaded methods are

1. String.Format(String first, Object second) Method
2. String.Format(String, params Object[]) Method
3. String.Format(IFormatProvider, String, Object) Method 
4. String.Format(IFormatProvider, String, Object, Object) Method  
5. String.Format(IFormatProvider, String, Object, Object, Object) Method
6. String.Format(IFormatProvider, String, Object[]) Method
7. String.Format(String, Object, Object) Method
8. String.Format(String, Object, Object, Object) Method

Example 6: To insert a single object in a string.

using System;  

namespace singleVariable {  
  class Example6 {
    public static void Main(string [] args) {

      int number = 8;
      // Format string
      string strFormat = String.Format("There are {0} mangoes in the basket.", number);
      Console.WriteLine(strFormat);
    }
  } 
}

Output 6:

Example 7: To insert multiple objects in a string.

using System;  

namespace multipleObject {  
  class Example7 {
    public static void Main(string [] args) {

      string name = "Rahul";
      string programmingLanguage = "Csharp";

      // Format the string
      string strFormat = String.Format("{0} likes to code in {1}", name, programmingLanguage);
      Console.WriteLine(strFormat);

      Console.ReadLine();
    }
  } 
}

Output 7:

StringBuilder.Append() in C#

In .NET, string objects are immutable. 

What does this imply? 
It means that every time you use one of the String class methods, whether, with the same or a different variable, a new string object is created in memory. This means that memory space in your computer's memory is reserved for that new string. 

The more string manipulation methods you use, the more memory space is allocated in memory. That is, in a string manipulation-heavy code, if strings are not used wisely, they can cause serious app performance issues.

.NET provides the System.Text.StringBuilder class that allows you to modify strings without creating new ones. StringBuilder is highly recommended if your code contains more than a few hundred string concatenation operations. StringBuilder should not be used for some string concatenation operations. StringBuilder class is defined in the System.Text namespace. This namespace must be imported into your class or referenced directly in the object instantiation.

Let us understand this method of “C# Concatenate Strings” with the help of an example.

Example 8:

using System;
using System.Text;
  
class Example8 {
  
    // Main Method
    public static void Main()
    {
        // The capacity is 25
        StringBuilder sampleString = new StringBuilder("Welcome to ", 25);
          
        sampleString.Append("Coding Ninjas, ");
        
        sampleString.Append("Hello Everyone!");
        Console.WriteLine(sampleString);
    }
}

Output 8:

Check out this article - C++ String Concatenation.

Frequently Asked Questions

How to add two strings together in C#?

To add two strings together in C#, you can use the + operator or the string.Concat() method. 

What is the best way to concat strings in C?

The best way to concatenate strings in C# is by using the StringBuilder class when dealing with large string manipulations. For smaller concatenations or simplicity, you can use the + operator or string.Concat().

Is string format quicker than C# concatenation?

Format (via Reflector) creates a StringBuilder and then calls AppendFormat on it. As a result, it is faster than concate for multiple strings.

What is the difference between append and concat in C#?

The difference between append and concat in C#, append is for efficiently building large strings using StringBuilder, avoiding many intermediate objects. On the other hand, concat in C# is for joining multiple strings into one, creating a new string object with string.Concat().

Conclusion

This blog discusses different ways to concatenate strings in C#. As we discussed a total of 6 methods: using + operator, using interpolation, using format(), join(), concatenate() methods, and using StringBuilder.Append() method. We looked at an example for each for clarity of concepts. Toward the end, we looked at some frequently asked questions on this topic. We hope that you got a clear understanding of C# Concatenate Strings.
Check out this problem - Longest String Chain

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