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Possible bug with range checking in StrUtils.IfThen function
BSaidus:
Hello.
Testing the following code in attached project raise an exception as shown in the screenshot.
The code
--- Code: Pascal [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---unit Unit1; {$mode objfpc}{$H+} interface uses Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls; type { TForm1 } TForm1 = class(TForm) Button1: TButton; cbParentIfs: TComboBox; Edit1: TEdit; procedure Button1Click(Sender: TObject); private public end; var Form1: TForm1; implementation uses StrUtils ; CONST CEth: array[0..4] of string = ('01','02','03','04','05'); {$R *.lfm} { TForm1 } procedure TForm1.Button1Click(Sender: TObject);var lIndex: Integer;begin lIndex := cbParentIfs.ItemIndex; Edit1.Text := IfThen( lIndex>=1, CEth[lIndex-1], 'tralllla');end; end.
PS: fpc 3.2.3 fixes, lazarus 2.2.7 fixes
Bart:
IIRC then all parameters of a function call will be evaluated.
So the expression CEth[lIndex-1] will be evaluated wether or not lIndex >= 1.
The fact that the function is called IfThen does not imply that boolean shortcutting is applied to it's parameter evaluation...
Bart
BSaidus:
--- Quote from: Bart on December 07, 2023, 11:22:59 pm ---IIRC then all parameters of a function call will be evaluated.
So the expression CEth[lIndex-1] will be evaluated wether or not lIndex >= 1.
The fact that the function is called IfThen does not imply that boolean shortcutting is applied to it's parameter evaluation...
Bart
--- End quote ---
Thanks for your answer.
Looking inside the code of IfThen in StrUtils, it do not looks (evaluate) the ATrue value if the condition is not sitisfied.
--- Code: Pascal [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---function IfThen(AValue: Boolean; const ATrue: string; const AFalse: string): string; begin if avalue then result:=atrue else result:=afalse;end;
Fibonacci:
Your code didnt work for me, I had to use specialize:
--- Code: Pascal [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---Edit1.Text := specialize IfThen<String>(lIndex>=1, CEth[lIndex-1], 'tralllla');
FPC trunk, no problems, no range errors
BSaidus:
--- Quote from: Fibonacci on December 07, 2023, 11:30:44 pm ---Your code didnt work for me, I had to use specialize:
--- Code: Pascal [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---Edit1.Text := specialize IfThen<String>(lIndex>=1, CEth[lIndex-1], 'tralllla');
FPC trunk, no problems, no range errors
--- End quote ---
Did you try to compile it in full debug mode ??
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