Colon Philosophy

[shadeclan]

No, I'm not talking about the one connected to your anus, moron!

In goto statements, it seems that colons are almost always optional. For example:

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goto:SomeLabel

... seems just as valid as ...

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goto SomeLabel

Only in cases of the implicit label EOF is it required:

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goto:EOF

My question is this - is there some advantage or disadvantage in colon usage? Has anyone found cases where a colon was or was not required in a goto statement?

See Ed? I still come here!

[nitt]

No, I'm not talking about the one connected to your anus, moron!

That wasn't that funny...

And you never need the colon with tags.


Assembly

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org 100h
tag:
mov ah, 09h
mov dx, msg
int 21
jmp tag

C++

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#include <iostream>
int main() {
tag:
std::cout << "hi";
goto tag;
}

Batch

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@echo off
:tag
echo hi
goto tag

[Rileyh]

Nitt,
There is no point in explaining the question in assembly.

org 100h
tag:
mov ah, 09h
mov dx, msg
int 21
jmp tag

And in most cases, the colon is not needed to goto a tag.

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goto a
(is the same as) goto :a

But it does not affect the capability of the code. I just use the colon out of habit.

[!k]

(is the same as) goto :a

until you do not use an editor with code coloring

[shadeclan]

No, I'm not talking about the one connected to your anus, moron!

That wasn't that funny...

Forgive the potty humor - I was trying to cut folks off "at the pass" as we say here in the US.

until you do not use an editor with code coloring

I, myself, use PSPad for batch editing. It does a pretty good job of highlighting except in two instances: indented labels, such as:

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:NormalLbl (normal highlighting)
...Code...
   :IndentedLbl (no highlighting)
   ...More code...

and internal function calls, such as:

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call:SomeFun (Label name is not highlighted)

It handles goto statements both with and without colons. By the way Ed, it actually supports a Dutch version!

[Ed Dyreen]

...
My question is this - is there some advantage or disadvantage in colon usage? Has anyone found cases where a colon was or was not required in a goto statement?

See Ed? I still come here!

The colon is no longer required since XP. It's still used in batches that need to be compatible !
Or was it the other way around ? Damnet now I am confused myself, there is a difference, otherwise I wouldn't have written code like:

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@rem :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
@rem:: Suppress all 'direct call' related errors, all Windows OSes.
@rem :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
@rem::(
@   if "%$ScriptHost.FullPathFile%"=="" 2>nul goto :ENDOLDOS ()
@   if "%$ScriptHost.FullPathFile%"=="" 2>nul goto  ENDOLDOS ()
@rem::)
@rem :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

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:ENDOLDOS ()
@rem ::
@rem :: Exit 'old' OS
@rem ::
@rem ::(
@rem    :: Initialize 'old' OS
@rem    ::(
@       echo Off
@rem    ::)

@rem    :: Print reason
@rem    ::(
@       echo.
@       echo. Direct call to SubRoutine not allowed ^!
@rem    ::)

@rem    :: Pause until user confirms
@rem    ::(
@      2>nul set "?= " <nul
@rem      ::
@      pause
@rem    ::)

@rem    :: CLearScreen may be needed to force close on exiting an 'old' OS
@rem    ::(
@      cls
@rem    ::)

@rem    :: OS may not support the 'exit error' command
@rem    ::(
@      2>nul exit 1
@rem    ::)

@rem    :: OS should support the 'goto EOF' command
@rem    ::(
@      goto EOF
@rem    ::)
@rem ::
goto EOF ()
@rem ::)

[shadeclan]

I was wondering when you'd show up!

now I am confused myself, there was a difference ...

Well, think about it and let me know.

[nitt]

Nitt,
There is no point in explaining the question in assembly.

-_- Is Assembly really the only one you noticed? Did you miss the C++ and Batch example?

My point was exactly what I said before it, that you never need to use the colon when "going to" a tag.

[shadeclan]

-_- Is Assembly really the only one you noticed? Did you miss the C++ and Batch example?

Actually, I noticed, although I am ignorant of any C language and don't know assembly .

Assembly has always fascinated me but I have never had the time to learn.

[nitt]

-_- Is Assembly really the only one you noticed? Did you miss the C++ and Batch example?

Actually, I noticed, although I am ignorant of any C language and don't know assembly .

Assembly has always fascinated me but I have never had the time to learn.

I don't know Assembly, either. But I know a lot of it.

http://www.youtube.com/watch?v=mWeh3_ITG7M

27 tutorials, and hopefully a 28th eventually, they break down all of what I know into the simplest of terms.

[shadeclan]

http://www.youtube.com/watch?v=mWeh3_ITG7M

27 tutorials, and hopefully a 28th eventually, they break down all of what I know into the simplest of terms.

Nice. Thanks - I'm saving the link. Assembly appears to be a dying skill but I have great respect for those who take the time to learn and use it.

[dbenham]

(original post deleted) Never mind - I was not distinguishing between GOTO LABEL vs. CALL LABEL.
Since GOTO LABEL without the colon works, I just assumed CALL LABEL works as well. Well it doesn't.

Dave Benham

[shadeclan]

(original post deleted) Never mind - I was not distinguishing between GOTO LABEL vs. CALL LABEL.
Since GOTO LABEL without the colon works, I just assumed CALL LABEL works as well. Well it doesn't.

Dave Benham

Yup.

Just for giggles, I tried calling a label in a batch job from a different batch job, ie: [call otherbatch.bat:otherlbl] - fortunately, it didn't work. I've learned a lot about batch scripting since I started frequenting this site - I've built beautiful libraries of routines I use every day. I would have been a little upset if I'd built the interface to those libraries for nothing or if there was a way to circumvent the interface - I do some error checking there.

[shadeclan]

Here's a thought. Since in the command "goto:eof" the colon is required, wouldn't it be a good idea to always use the colon for other labels so that, if you are a sieve-mind like myself, you don't forget it when coding "goto:eof"?

[aGerman]

:eof is no label. It's only a virtual expression which tells the parser to jump to the end of file. For that reason only for goto :eof needs the colon.

Regards
aGerman