Shouldn't this return an empty string?

[Mistrel]

I'm writing a preceding null in front of the string I'm poking. Shouldn't I get a blank string? The character doesn't seem to be written at all.

Code: Select all

*Mem=AllocateMemory(500)

String.s=""
For i=1 To 6
  String.s+"7"
Next i

;/ No preceding null is written
PokeS(*Mem+16,Chr(0)+String.s,Len(String.s)+1)

;/ Chr(6) is correctly written
;PokeS(*Mem+16,Chr(6)+String.s,Len(String.s)+1)

Debug PeekS(*Mem+16)

Debug PeekC(*Mem+16)

[IdeasVacuum]

Try this:

Code: Select all

PokeS(*Mem, Chr(Null) + sString, (Len(sString) + 2) )

[Demivec]

I'm writing a preceding null in front of the string I'm poking. Shouldn't I get a blank string? The character doesn't seem to be written at all.

A null, or Chr(0), isn't a string it's a terminator. It shows the end of a string. That being said, I agree that it should function as you expected.

Compare these two:

Code: Select all

string.s = "777777"
;/ No preceding null is written
PokeS(*Mem+16,Chr(0)+string.s,Len(string.s)+1)
Debug PeekS(*Mem+16)
Debug PeekC(*Mem+16)

;/It works as you would expect with a string constant
PokeS(*Mem+16,Chr(0)+"333",Len("333")+1)
Debug PeekS(*Mem+16)
Debug PeekC(*Mem+16)

It looks like it may be a bug.

[IdeasVacuum]

A zero could be a bona fide member of a string? I don't know, but Null = Null and should always work.

[Vitor_Boss®]

I'm writing a preceding null in front of the string I'm poking. Shouldn't I get a blank string? The character doesn't seem to be written at all.

A null, or Chr(0), isn't a string it's a terminator. It shows the end of a string. That being said, I agree that it should function as you expected.

Compare these two:

Code: Select all

string.s = "777777"
;/ No preceding null is written
PokeS(*Mem+16,Chr(0)+string.s,Len(string.s)+1)
Debug PeekS(*Mem+16)
Debug PeekC(*Mem+16)

;/It works as you would expect with a string constant
PokeS(*Mem+16,Chr(0)+"333",Len("333")+1)
Debug PeekS(*Mem+16)
Debug PeekC(*Mem+16)

It looks like it may be a bug.

If first code are compiled in ASCII the NULL char isn't write? On Unicode mode all char less than 255 use a Char(0) before the number, like 00FF for Chr(255), you tried use double null chars in unicode programs?

[freak]

Chr(0) is cannot be part of a string. It marks the end of a string. So all you get is an empty string.

> Chr(0)+string.s

You add nothing to the beginning string.s. So you end up with the original string.

> Chr(0)+"333"

The reason this seems to work is because it is resolved at compile-time. Its a side-effect of the optimization for literal Chr() calls.

[Mistrel]

You add nothing to the beginning string.s. So you end up with the original string.

I guess it makes sense. Chr(0) resolves to an empty string.

That's not exactly what I was expecting but it is the logical result. I've adjusted my code to PokeC the null and then PokeS the string.

The reason this seems to work is because it is resolved at compile-time. Its a side-effect of the optimization for literal Chr() calls.

Would you classify this as an actual bug or an acceptable one?

[IdeasVacuum]

...I think we have all missed the obvious question then - why are you trying to prefix a null?