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#### CompareChar

Declaration:
  function CompareChar(var buf1,buf2;len:longint):longint; function CompareChar0(var buf1,buf2;len:longint):longint;
Description:
  CompareChar compares two memory regions buf1,buf2 on a character-per-character basis for a total of len characters.

  The CompareChar0 variant compares len bytes, or until a zero character is found.

  The function returns one of the following values:

  -1
    if buf1 and buf2 contain different characters in the first len positions, and the first such character is smaller in buf1 than the character at the same position in buf2.
  0
    if the first len characters in buf1 and buf2 are equal.
  1
    if buf1 and buf2 contain different characters in the first len positions, and the first such character is larger in buf1 than the character at the same position in buf2.
Errors:
  None.
See also:
  CompareByte (466),CompareWord (472),CompareDWord (470)

Listing: refex/ex100.pp

Program Example100;
{ Program to demonstrate the CompareChar function. }
Const
ArraySize = 100;
HalfArraySize = ArraySize Div 2;
Var
Buf1,Buf2 : Array[1..ArraySize] of char;
I : longint;
Procedure CheckPos(Len : Longint);
Begin
Write('First ',Len,' characters are ');
if CompareChar(Buf1,Buf2,Len)<>0 then
Write('NOT ');
Writeln('equal');
end;
Procedure CheckNullPos(Len : Longint);
Begin
Write('First ',Len,' non-null characters are ');
if CompareChar0(Buf1,Buf2,Len)<>0 then
Write('NOT ');
Writeln('equal');
end;
begin
For I:=1 to ArraySize do
begin
Buf1[i]:=chr(I);
If I<=HalfArraySize Then
Buf2[I]:=chr(I)
else
Buf2[i]:=chr(HalfArraySize-I);
end;
CheckPos(HalfArraySize div 2);
CheckPos(HalfArraySize);
CheckPos(HalfArraySize+1);
CheckPos(HalfArraySize + HalfArraySize Div 2);
For I:=1 to 4 do
begin
buf1[Random(ArraySize)+1]:=Chr(0);
buf2[Random(ArraySize)+1]:=Chr(0);
end;
Randomize;
CheckNullPos(HalfArraySize div 2);
CheckNullPos(HalfArraySize);
CheckNullPos(HalfArraySize+1);
CheckNullPos(HalfArraySize + HalfArraySize Div 2);
end.

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