Posted on 31st Mar 2018 in Delphi FMX
So here I was upgrading an App that used TCharacter in Berlin 10.1. Next thing a warning message is shown?
[dcc32 Warning] Unit4.pas(50): W1000 Symbol 'TCharacter' is deprecated: 'Use TCharHelper'…
I have learnt that when you see this in the IDE, it is best to make the changes immediately or else you will find that when you upgrade later the app will fail. When applying some simple changes the results were not as transparent as it would seem and there is very little documentation to support as to why these errors were present and I delved deeper into the code.
Why is TCharacter being deprecated, well it seems that both uses the latest definitions of Unicode character type data, and it is good to know that it can convert Unicode characters from UTF-32 to UTF-16, and backwards.
So what are the differences actually?
Well TCharset checks for a zero string range and TCharacter check string range. This will catch you out in you code if you using a for-loop through the string and present an error.
TCharset is using a UCS4Char which works with 4–byte Unicode characters.
So the original test code looks like this...
implementation uses System.Character; var LNumber,LLength,LLetters,LLower,LUpper,I:integer; str:String; begin str:= '123456789abcdefABCDEF'; LNumber:= 0; LLength:= 0; LLetters := 0; LLower := 0; LUpper := 0; memo1.Lines.Add('String Length: '+Length(str).tostring); memo1.Lines.Add(''); for I := 1 to Length(Str) do begin if TCharacter.IsNumber(Str,I) then Inc(LNumber); if Tcharacter.isletter(Str,I) then Inc(LLetters); if Tcharacter.IsLower(Str,I) then Inc(LLower); if Tcharacter.IsUpper(Str,I) then Inc(LUpper); end;
Making the direct change with TCharhelper will result with a debugger notice…
What are these errors?
As you can see that the Zero checking with TCharHelper will create an error if you do not change the Length(str) – 1 from normal string checking Length(Str) .
‘Event Log = First chance exception at $76A5CBB2. Exception class EArgumentOutOfRangeException with message 'String index out of range (21). Must be >= 0 and <= 20'. ….(7076) ‘.
Why did Embarcadero change the range format? I am out of answers as to why this was implemented and could be a different coding approach.
The new code evolves to the following..
implementation uses System.Character; var LNumber,LLength,LLetters,LLower,LUpper,I:integer; str:String; CharHelper:Char; // added to the code begin str:= '123456789abcdefABCDEF'; LNumber:= 0; LLength:= 0; LLetters := 0; LLower := 0; LUpper := 0; memo2.Lines.Add('String Length: '+Length(str).tostring); memo2.Lines.Add(''); for I := 0 to Length(Str) -1 do // changing this to length str -1 will adjust for zerocheckingstr change begin if CharHelper.IsNumber(Str,I) then Inc(LNumber); if CharHelper.IsLetter(Str,I) then Inc(LLetters); if CharHelper.IsLower(Str,I) then Inc(LLower); if CharHelper.IsUpper(Str,I) then Inc(LUpper); end; memo2.Lines.Add('Number '+LNumber.tostring); memo2.Lines.Add('Total Letters '+LLetters.tostring); memo2.Lines.Add('Lower '+LLower.tostring); memo2.Lines.Add('Upper '+Lupper.tostring); end;
So how does this effect mobile? This change works perfectly cross-Platform and works as it did before.
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