How to concatenate multiple strings in C#

String concatenation in C# is the process of combining two or more strings to create a new string. There are several ways to concatenate strings in C#.

Using the + Operator

The + operator can be used to concatenate strings.

string firstName = "Emil"; string lastName = "Williams"; string fullName = firstName + " " + lastName;

In this example, the + operator combines the firstName and lastName strings with a space in between to create fullName.

Using the string.Concat Method

The string.Concat method can concatenate multiple strings.

string str1 = "Hello, "; string str2 = "world!"; string message = string.Concat(str1, str2);

This method is useful when you want to concatenate more than two strings.

Using Interpolation

String interpolation allows you to embed expressions and variables within a string.

string name = "Mary"; int age = 35; string message = $"My name is {name} and I am {age} years old.";

In this example, the values of name and age are inserted into the string using {}.

Using StringBuilder

For concatenating strings in a loop or when dealing with many string manipulations, StringBuilder is more efficient because it avoids creating unnecessary string objects.

using System.Text; StringBuilder sb = new StringBuilder(); sb.Append("This "); sb.Append("is "); sb.Append("a "); sb.Append("long "); sb.Append("string."); string result = sb.ToString();

StringBuilder is mutable, allowing efficient appending of strings without creating new instances.

Using string.Join

You can use string.Join to concatenate elements of an array or collection with a separator.

string[] fruits = { "apple", "banana", "cherry" }; string concatenated = string.Join(", ", fruits);

In this example, string.Join combines the array elements with ", " as the separator.

Here are some other things to keep in mind when concatenating strings in C#:

  1. When concatenating strings using the + operator, both strings must be of the string type. If one or more of the strings is not of the string type, the compiler will generate an error.
  2. The String.Concat() method can be used to concatenate any number of strings, regardless of their type.
  3. The String.Concat() method also has a number of overloaded versions that can be used to concatenate strings with other types of data, such as numbers and objects.


String concatenation in C# involves combining two or more strings to create a new string. This can be achieved using operators like +, methods like string.Concat, string interpolation, or StringBuilder for efficient concatenation, and it is a fundamental operation for constructing and manipulating strings in C# applications.