C# String CopyTo() Method (original) (raw)

Last Updated : 18 Mar, 2025

In C#, the **CopyTo() is a method of String Class. It is used to copy a specified number of characters from a specified position in the string and it copies the characters of this string into an array of Unicode characters.

**Example 1: Using the CopyTo() method to copy characters from a string to a character array.

C# `

// C# program to illustrate the // String.CopyTo() Method // Method using System;

class Geeks { public static void Main() { // Creating a string string s = "GeeksForGeeks";

    // Destination char array
    char[] dest = new char[3];

    //Copying 3 characters from the 5th index 
    //of the string to the destination char array.
    s.CopyTo(5, dest, 0, 3);
    
    // Displaying the copied string
    Console.WriteLine($"The Copied String is: {new string(dest)}");
}

}

`

Output

The Copied String is: For

Syntax of String CopyTo() Method

public void CopyTo(int sourceIndex, char[] destination, int destinationIndex, int count)

**Parameters:

• **sourceIndex: Index of String to be copied. Its type is System.Int32 .
• **destination: It is the array of Unicode characters to which characters will be copied. Its type is System.Char[].
• **destinationIndex: It is the the starting index of the array from where the copy operation begins. Its type is System.Int32.
• **count: It is the number of characters which will copy to the destination. Its type is System.Int32.

**Exceptions:

• **ArgumentNullException: If the destination array is null then it will throw this Exception.
• **ArgumentOutOfRangeException: There are different cases when an exception occurs
  • If sourceIndex, destinationIndex, or count is negative.
  • If sourceIndex does not identify a position in the current instance.
  • If destinationIndex does not identify a valid index in the destination array.
  • If the count is greater than the length of the substring from startIndex to the end of this instance
  • If the count is greater than the length of the subarray from destinationIndex to the end of the destination array.

**Example 2: Using the CopyTo() method to modify an existing character array.

C# `

// C# program to illustrate the // ToCopy() string method using System;

class Geeks {

public static void Main() 
{ 
    string s = "GeeksForGeeks"; 
    
    char[] dest = {'H', 'e', 'l', 'l', 'o', ' ', 
                   'W', 'o', 'r', 'l', 'd' }; 

    // str index 8 to 8 + 5 has 
    // to copy into Copystring 
    // 5 is no of character 
    // 6 is start index of Copystring 
    s.CopyTo(8, dest, 6, 5); 
    
    // Displaying the result 
    Console.Write("String Copied in dest is: "); 
    Console.WriteLine(dest); 
} 

}

`

Output

String Copied in dest is: Hello Geeks