What is the difference between String.Copy() and String.CopyTo() methods in C#?

The String.Copy() and String.CopyTo() methods in C# serve different purposes for copying string data. String.Copy() creates a new string object with the same content, while String.CopyTo() copies characters from a string into a character array.

Syntax

Following is the syntax for String.Copy() method −

public static string Copy(string str)

Following is the syntax for String.CopyTo() method −

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

Parameters

String.Copy() Parameters:

• str − The string to copy.

String.CopyTo() Parameters:

• sourceIndex − The index of the first character to copy from the string.

• destination − The character array to copy characters into.

• destinationIndex − The starting index in the destination array.

• count − The number of characters to copy.

Using String.Copy()

The String.Copy() method creates a new string object with the same content as the original string −

Example

using System;

class Demo {
   static void Main(String[] args) {
      string str1 = "Welcome!";
      string str2 = "user";
      str2 = String.Copy(str1);

      Console.WriteLine("Original string: " + str1);
      Console.WriteLine("Copied string: " + str2);
      Console.WriteLine("Are they equal? " + (str1 == str2));
      Console.WriteLine("Are they same reference? " + ReferenceEquals(str1, str2));
   }
}

The output of the above code is −

Original string: Welcome!
Copied string: Welcome!
Are they equal? True
Are they same reference? False

Using String.CopyTo()

The String.CopyTo() method copies characters from a string into a character array at a specified position −

Example

using System;

class Demo {
   static void Main(String[] args) {
      string str = "This is it!";
      char[] ch = new char[5];

      // Copy 2 characters starting from index 2 of string to index 0 of array
      str.CopyTo(2, ch, 0, 2);

      Console.WriteLine("Original string: " + str);
      Console.WriteLine("Character array: " + new string(ch));
      Console.WriteLine("First two chars: " + ch[0] + ch[1]);
   }
}

The output of the above code is −

Original string: This is it!
Character array: is
First two chars: is

Copying Multiple Segments

Example

using System;

class Demo {
   static void Main(String[] args) {
      string str = "Hello World";
      char[] buffer = new char[10];

      // Copy "Hello" (first 5 characters)
      str.CopyTo(0, buffer, 0, 5);
      
      // Copy "World" (last 5 characters starting from index 6)
      str.CopyTo(6, buffer, 5, 5);

      Console.WriteLine("Original string: " + str);
      Console.WriteLine("Buffer content: " + new string(buffer));
   }
}

The output of the above code is −

Original string: Hello World
Buffer content: HelloWorld

Comparison

Conclusion

String.Copy() creates a new string object with identical content, while String.CopyTo() extracts specific characters from a string into a character array. Use Copy() for duplicating strings and CopyTo() for selective character extraction into arrays.