How do you convert a char to a byte?

[Pasqualish]

I want to do Shr on a char. But it doesn't allow that. I can do it on a byte, however I can't directly assign a char to a byte. Is there syntax to cast a char to a byte?

[molly]

I'm a bit surprised with that question as you already did in your previously question in which you shared some of your code. But perhaps i misunderstood your question here ?

Code: [Select]

var
  x : Char;
  y : Byte;
begin
  x := 'a';
  y := Ord(x);
  writeln(y);
  y := Byte(x);
  writeln(y); 
  y := ord(x) shr 1;
end.


[sam707]

Code: Pascal  [Select][+][-]

1. var a: char;
2. begin
3.  
4.   a:='x';
5.   { the following line is what you are looking for }
6.   a:= chr(byte(a) shr 1);
7. end;  
8.  

the transtyping of variable a from type char to byte is : "byte(a)"
cast done.

[Pasqualish]

the transtyping of variable a from type char to is : "byte(a)"

Thanks! So I guess - in cases where it is possible - the Pascal "cast" would be in that form for all values such as Integer(a), LongInt(a) etc.

[Pasqualish]

I'm a bit surprised with that question as you already did in your previously question in which you shared some of your code. But perhaps i misunderstood your question here ?

No, you are correct. I  looked at my output erroneously and decided that Ord() had produced the wrong result.

[sam707]

transtyping ... casting from simple type to another is type(value) so, you did guess it right way!

Enjoy

[sam707]

Ord like Chr are system unit functions, unlike casting from type to type, they arn't usually resolved at compile time but called at run time... that is why you should prefer for faster code Char(value) as Chr(value) , Byte(value) as Ord(value)

[molly]

@Pasqualish
Ok, no problem. thank you for having taken the time to clear that up. Another mystery solved 

Wrong interpretation of results is something that happens to each and all of us one time or another. Can be very hazardous, although it keeps things exciting 

[Thaddy]

Note all examples given are not really portable because in all cases it is assumed that char is AnsiChar, which is not always the case.
So declare it as AnsiChar, plz.

Code: Pascal  [Select][+][-]

1. program charshift;
2. {$APPTYPE CONSOLE}
3. begin
4.   writeln(AnsiChar(Byte(AnsiChar('z')) shr 1)); // should be '='
5.   readln;
6. end.

The AnsiChar casts are not necessary on Ansi systems, but is on systems where the string literal is an unicode encoding and where Char is WideChar.

[sam707]

Note all examples given are not really portable because in all cases it is assumed that char is AnsiChar, which is not always the case.
So declare it as AnsiChar, plz.

Code: Pascal  [Select][+][-]

1. program charshift;
2. {$APPTYPE CONSOLE}
3. begin
4.   writeln(AnsiChar(Byte(AnsiChar('z')) shr 1)); // should be '='
5.   readln;
6. end.

The AnsiChar casts are not necessary on Ansi systems, but is on systems where the string literal is an unicode encoding and where Char is WideChar.

we could discuss a whole book long on what is portable or not because ansichar did NOT exist when Turbo pascal normalized what a byte or a char was, and even the "type(value) to cast from type to type is NOT part of the Pascal language 1st syntax form, that is

var a: char;
var b: byte;

begin

...
b := a as byte;

end;

SO!!! as it works and it is understandable, the conversation around AnsiChar, WideChar, UTF8Char, WHATEVERChar, and I8n internationalization would be apart, and on another chapter of a neverending book that I wont troll with anyone...

USELESS!! and cumbersome, at this point

[sam707]

what is portable a day, can be no more portable 10 years later and et cetera 

[Thaddy]

what is portable a day, can be no more portable 10 years later and et cetera 

Yes, but in this case it is all the more true: char in the sense of the olden days of TurboPascal should be considered deprecated. So in the modern times you should use AnsiChar, not Char.
Just because Char is not guaranteed to be one byte anymore. So, yes, your last statement is true and you should use AnsiChar in modern code. That will make your sourcecode a lot more portable between systems for a long time to come. Just define {$delphiunicode} or {$modeswitch unicodestrings} and compile and run your char examples.... Then do the same with proper AnsiChar declarations, then it works again as expected. Keep using char if you want to introduce hard to find bugs in your sourcecode. By all means

[sam707]

dear @Thaddy, the original post was an easy question, answered with 1 line of code and, as I just told you, you are at the begining of a whole book around a single byte (?!?!?! LOL), furthermore bluring the original subject and going ahead with useless considerations regarding the original very 1st question... could you, please, keep concentrated on one point only? it seems not. Nevermind, but I seriously think you are the kind of person who always feel the need to get the last word, even if you make people waste their time and get lost around DIFFERENT subjects

[sam707]

when I read a post with answers that ALREADY gave the response, I might be lazy, but I do not write'n'troll
BYE
Regards

[sam707]

nothing personal, i saw many many many people here, extending comments and comments, while its unnecessary... so just did I, but its rare from me I beg your pardon