什么是String.CopyTo？

Question

Can any one explain why the output of this code is only 'hello' and what this code means?

( 0, characterArray, 0, characterArray.Length );

The output is showing:

The character array is: hello

The code follows:

string string1 = "hello there";
char[] characterArray = new char[ 5 ];

string1.CopyTo( 0, characterArray, 0, characterArray.Length );
Console.Write( "\nThe character array is: " );

for ( int i = 0; i < characterArray.Length; i++ )
    Console.Write( characterArray[ i ] );

Answer 1

It's because your array is only set for 5 characters. Expand it to 11 and it will work.

Here is what the Copyto is:

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

Parameters
sourceIndex
Type: System..::.Int32
A character position in this instance. 

destination
Type: array[]()[]
An array of Unicode characters. 

destinationIndex
Type: System..::.Int32
An array element in destination. 

count
Type: System..::.Int32
The number of characters in this instance to copy to destination.

Taken from: http://msdn.microsoft.com/en-us/library/system.string.copyto.aspx

Answer 2

It's only showing 'hello' because your character array is only 5 chars long. As for the parameters to CopyTo, read http://msdn.microsoft.com/en-us/library/system.string.copyto.aspx

Answer 3

这是因为您的字符数组大小仅为5。如果您希望将整个字符串作为数组，则可以string.ToCharArray代替。