Thursday, March 3, 2011

What is a equivalent of Delphi FillChar in C#?

Hello,

This is my first question so I would like to say hello to everyone.

My friend was programming in Delphi. Now he is learning C# and asked me, if I know C# eqivalent of Delphi's FillChar.

Could you please help me to help him?

Kind regards

From stackoverflow
  • If I understand FillChar correctly, it sets all elements of an array to the same value, yes?

    In which case, unless the value is 0, you probably have to loop:

    for(int i = 0 ; i < arr.Length ; i++) {
        arr[i] = value;
    }
    

    For setting the values to the type's 0, there is Array.Clear

    Obviously, with the loop answer you can stick this code in a utility method if you need... for example, as an extension method:

    public static void FillChar<T>(this T[] arr, T value) {...}
    

    Then you can use:

    int[] data = {1,2,3,4,5};
    //...
    data.FillChar(7);
    

    If you absolutely must have block operations, then Buffer.BlockCopy can be used to blit data between array locatiosn - for example, you could write the first chunk, then blit it a few times to fill the bulk of the array.

    Gamecat : FillChar fills a structure (any one) with a given length with the same value. It is not the most descriptive name in the Delphi library but is has been around for a long time.
    Marc Gravell : @Gamecat - to overwrite *any* structure, you would probably need to use unsafe code and simply write over it... the question would be: why?
  • Try this in C#:

    String text = "hello";
    text.PadRight(10, 'h').ToCharArray();
    
  • I'm assuming you want to fill a byte array with zeros (as that's what FillChar is mostly used for in Delphi).

    .NET is guaranteed to initialize all the values in a byte array to zero on creation, so generally FillChar in .NET isn't necessary.

    So saying:

    byte[] buffer = new byte[1024];
    

    will create a buffer of 1024 zero bytes.

    If you need to zero the bytes after the buffer has been used, you could consider just discarding your byte array and declaring a new one (that's if you don't mind having the GC work a bit harder cleaning up after you).

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