From Clomosy Docs
procedure Dec(var X: Integer); overload;
The Dec procedure decrements the ordinal Variable parameter passed to it.
Example
var
Number : Integer;
{
Number = 23;
ShowMessage('Number : '+IntToStr(Number));
Dec(Number);
ShowMessage('Number-1 : '+IntToStr(Number));
}
Output:
Number : 23
Number-1 : 22