[Lazarus] How to check if a string is a valid floating-point number.

[Michael Van Canneyt]

You should use the default TryStrToFloat() function from the sysutils unit. 
It does exactly that, without exceptions.

The function result may change if the internationalization/localization 
settings have changed. e.g. if you switch from platform.

Secondly, please note that in the debugger you will always 'see' the 
exception before it is caught in the exception handler.

Michael.


On Fri, 25 Nov 2011, Kjow wrote:

> Hi all,
>
> I need to know if a string is a valid floating-point number, so I
> tried this function:
>
> function IsStrFloatNum(s: string): Boolean;
> begin
>  try
>    // try to convert the string into a floatnumber
>    StrToFloat(s);
>    // if there is no error the result is true
>    Result := True;
>  except
>    // if there is any error the result is false
>    Result := False;
>  end;
> end;
>
> (From: http://www.swissdelphicenter.ch/torry/showcode.php?id=304 )
>
> Well, I get this error:
>
> Debugger Exception Notification
> project.exe raised exception class 'EConvertError' with message:
> "Cross" is an invalid float
>
> I used this function some month ago in this project and it worked
> without problems, but now (some month after) I re-tried to re-build
> and re-use this function and I get this error.
>
> Did I inadvertently change something?
>
>
> Thank you!
> Kjow
>
> --
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