[fpc-pascal] BoolToStr

Michael Van Canneyt michael at freepascal.org
Sun Aug 28 17:39:21 CEST 2022

On Sun, 28 Aug 2022, James Richters via fpc-pascal wrote:

> I'm generating a report where I wish to display some Boolean values.  I
> thought I would try BoolToStr, as according to:
> https://www.freepascal.org/docs-html/rtl/sysutils/booltostr.html it states:
> Description
> BoolToStr converts the boolean B to one of the strings 'TRUE' or 'FALSE'
> So it should do exactly what I want. output the text string 'TRUE' or
> 'FALSE'  depending on the Boolean state,
> but that is not what happens:
> Uses Sysutils;
> Begin
> Writeln(BooltoStr(True));
> Writeln(BooltoStr(False));
> End.
> Running "i:\booltostr.exe "
> -1
> 0
> Why true is -1 instead of 1 is beyond me, but anyway, I would consider this
> BoolToInt, not BoolToStr,  I want the Strings 'TRUE' or 'FALSE' as indicated
> in the documentation

I will adapt the documentation to be more precies.

You can use



in which case it will use the BoolStrs arrays to determine the strings.

-1 and 0 are the Delphi values, which, I agree,  are not very intuitive.

> And BoolToInt should always output 0 or 1, not matter what operating system
> you are on.. I don't understand the -1.  I guess some Windows API's use -1
> for true.. I still don't understand.
> Maybe there should be a BoolToBit that could always be 0 or 1 regardless of
> the operating system.

As said, the 0 and -1 are for Delphi compatibility.



It will give you 0 and 1.


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