In any programs, a lot of tests on empty strings are made. The following made the work :
if Length(s) 0 then ...
or
if s '' then ...

In a lot of cases, the real length is no needed, just to know if the string is empty or not.
I am mainly using UTF8String so strings with leading zero. Just with the first char we can know if the string is empty or not.

Is there a function of this kind that I don't know already exist ? Would it be possible to implement such a function (may be a stupid idea for an unknown reason) ?
Can this function be directly done in FPC ?

Regards.

Doesn't FillChar/Word/Byte works for you ?

Ido

You can try access a UTF8String lika a array.

So, you can replace your test by

if mystringvar[0] '' then ...

I thought string should be accessed from 1 not 0 for compatibility. And it is what I am doing.

for i := 1 to length(s) do ...

so I am not sure that using s[0] is safe

If memory serves, the [0] element was originally used to hold a byte that was equivalent to the string length. This was in the Turbo Pascal days though. I don't recall if that behavior was carried over into Delphi or the Delphi mode of FPC.

g.

-- Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.

To the OP: are you using the AnsiString as a buffer (that contains "several" strings)? Otherwise, using "MyString '' " would do because #0 is only valid as terminator in UTF-8 too.

BTW, IIRC Delphi would generate faster code for the above construction instead of "Length(MyString) 0" because of locking.

s[0] won't compile. Not in Delphi, at least.

That's correct, but for ShortStrings only.

Best regards,
Flávio

ik wrote

Doesn't FillChar/Word/Byte works for you ?

I don't think any of them made my purpose.

That is what "if s '' then" checks for. This is already generated as optimally as possible.

Jonas

In a previous thread, I have ask the difference between (Length(s) =
0) and (s = '')

Copy paste a answer :

Consequently, it can not be the same code. Otherwise I understood nothing :)

I don't understand your question. Above, you say that these statements work:

>> if Length(s) 0 then ... >> or >> if s '' then ...

(or does "made the work" mean something else?). If that indeed works, then everything is fine, because
a) both indeed generate the same code
b) both check whether the string is empty or not (without actually looking at the length)

Jonas

Consequently, it can not be the same code. Otherwise I understood nothing :)

'' is an empty string, _and_ its length is zero (of course). So the compiler is so intelligent as to replace length(s) = 0, or s = '' by the same code.

Normally s = '' would be a very slow way to check for an empty string, so the compiler optimizes this automatically.

John

Thanks !

Sorry for my question not so clear :)