C# StringBuilder

StringBuilder is a dynamic object used to handle mutable strings in C#. Unlike the immutable String class which creates a new object after every modification, StringBuilder updates the existing buffer and expands its memory as needed. This makes it suitable for scenarios involving frequent concatenation, insertion or removal operations.

Declaration and Initialization

StringBuilder is declared and initialized like any other class.

StringBuilder s = new StringBuilder();

or

StringBuilder s = new StringBuilder("GeeksForGeeks");

The variable s refers to an instance of the StringBuilder class. A string value can also be passed directly to its constructor.

Defining capacity

Although StringBuilder grows dynamically, you can specify its initial capacity which indicates the maximum number of characters it can hold before resizing.

StringBuilder s = new StringBuilder(20);

or

StringBuilder s = new StringBuilder("GeeksForGeeks", 20);

• In the first constructor an integer is passed representing the initial capacity.
• In the second constructor a string and a capacity value are provided.

Important Methods of StringBuilder

Example 1: Append Values

using System;
using System.Text;

class Geeks {
    public static void Main() {

        StringBuilder s = new StringBuilder("HELLO ", 20);

        s.Append("GFG");
        s.AppendLine("GEEKS");
        s.Append("GeeksForGeeks");

        Console.WriteLine(s);
    }
}

HELLO GFGGEEKS
GeeksForGeeks

Example 2: AppendFormat

using System;
using System.Text;

class Geeks {
    public static void Main() {

        StringBuilder s = new StringBuilder("Your total amount is ");

        s.AppendFormat("{0:C} ", 50);

        Console.WriteLine(s);
    }
}

Your total amount is ?50.00 

Example 3: Insert at Specific Index

using System;
using System.Text;

class Geeks {
    public static void Main() {

        StringBuilder s = new StringBuilder("HELLO ", 20);

        s.Insert(6, "GEEKS");

        Console.WriteLine(s);
    }
}

HELLO GEEKS

Example 4: Remove Characters

using System;
using System.Text;

class Geeks {
    public static void Main() {

        StringBuilder s = new StringBuilder("GeeksForGeeks", 20);

        s.Remove(5, 3);

        Console.WriteLine(s);
    }
}

GeeksGeeks

Example 5: Replace Characters

using System;
using System.Text;

class Geeks {
    public static void Main() {

        StringBuilder s = new StringBuilder("GFG Geeks ", 20);

        s.Replace("GFG", "Geeks For");

        Console.WriteLine(s);
    }
}

Geeks For Geeks