Delphi Basics : FillChar command

DelphiBasics

FillChar
Procedure

Fills out a section of storage with a fill character or byte value

System unit

procedure FillChar(var Buffer; FillCount Integer; FillValue Byte);

Description

The FillChar procedure fills out a section of storage Buffer with the same byte or character FillValue FillCount times.

It is principally used to initialise arrays of numbers. It can be used to initialise records and strings, but care should be used to avoid overwriting length fields. StringOfChar is best for filling out strings to the same character.

Related commands

GetMem		Get a specified number of storage bytes
SetString		Copies characters from a buffer into a string
StringOfChar		Creates a string with one character repeated many times

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Example code : Fill out a word array

var
  data : array[0..3] of Word;
  i : Integer;

begin
  // Fill out the Word array
  ShowMessage('Before FillChar :');
  for i := 0 to 3 do
  begin
    data[i] := i*5;
    ShowMessage(IntToStr(i)+' element value = '+IntToStr(data[i]));
  end;

  // Now fill out the array with the value 1
  // A Word is 2 bytes : 00000001 00000001 hex = 257 decimal
  FillChar(data, 4*SizeOf(Word), 1);

  // And show the array now
  ShowMessage('After FillChar :');
  for i := 0 to 3 do
    ShowMessage(IntToStr(i)+' element value = '+IntToStr(data[i]));
end;

Show full unit code

  Before FillChar :
  0 element value = 0
  1 element value = 5
  2 element value = 10
  3 element value = 15
  After FillChar :
  0 element value = 257
  1 element value = 257
  2 element value = 257
  3 element value = 257