Macro function with void argument list

[Martin Wells]

Is there any way of achieving this? Something like:

#define END_SCAN() (EndScan(),CleanUpAfterScan())

(Yes I realise this doesn't work)

I want to be able to invoke it as:

END_SCAN();

rather than:

END_SCAN;

Martin

[Keith Willis]

Martin Wells wrote:

Is there any way of achieving this? Something like:

#define END_SCAN() (EndScan(),CleanUpAfterScan())

(Yes I realise this doesn't work)

The idiom that I normally use is:

#define END_SCAN() do{EndScan();CleanUpAfterScan();}while(0)

[Eric Sosman]

Martin Wells wrote:

Is there any way of achieving this? Something like:

#define END_SCAN() (EndScan(),CleanUpAfterScan())

(Yes I realise this doesn't work)

In what way does it fail to work?

I want to be able to invoke it as:

END_SCAN();

rather than:

END_SCAN;

I don't see what's stopping you. Maybe more context
would clarify the problem.

--
Eric Sosman
es*****@ieee-dot-org.invalid

[Philip Potter]

Keith Willis wrote:

Martin Wells wrote:

>Is there any way of achieving this? Something like:

#define END_SCAN() (EndScan(),CleanUpAfterScan())

(Yes I realise this doesn't work)

The idiom that I normally use is:

#define END_SCAN() do{EndScan();CleanUpAfterScan();}while(0)

Why bother with the unnecessary do/while? Just use a bare block.

[Christopher Benson-Manica]

[comp.lang.c] Philip Potter <pg*@see.sig.invalidwrote:

Keith Willis wrote:

>#define END_SCAN() do{EndScan();CleanUpAfterScan();}while(0)

Why bother with the unnecessary do/while? Just use a bare block.

The FAQ explains why a bare block is not good enough:
http://c-faq.com/cpp/multistmt.html

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[Kenneth Brody]

Martin Wells wrote:

>
Is there any way of achieving this? Something like:

#define END_SCAN() (EndScan(),CleanUpAfterScan())

(Yes I realise this doesn't work)

Define "doesn't work".

I want to be able to invoke it as:

END_SCAN();

rather than:

END_SCAN;

What happens when you define END_SCAN() as above, and invoke is as
END_SCAN(); as desired?

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Don't e-mail me at: <mailto:Th*************@gmail.com>

[Martin Wells]

Eric:

I don't see what's stopping you. Maybe more context
would clarify the problem.

Oh I didn't realise that that's actually possible. My compiler puked
the first time I tried it... I'll try it again tomorrow.

Martin

[Keith Thompson]

Christopher Benson-Manica <at***@faeroes.freeshell.orgwrites:

[comp.lang.c] Philip Potter <pg*@see.sig.invalidwrote:

>Keith Willis wrote:

>>#define END_SCAN() do{EndScan();CleanUpAfterScan();}while(0)

>Why bother with the unnecessary do/while? Just use a bare block.

The FAQ explains why a bare block is not good enough:
http://c-faq.com/cpp/multistmt.html

But in this particular case, a block isn't necessary at all, since the
expansion contains only function calls (which are expressions, only
becoming statements when you add a semicolon).

#define END_SCAN() ( End_Scan(), CleanUpAfterScan() )

You only need a block when the expansion contains control flow. Even
then, an if/else statement can often be replaced with a ?: operator.

I recommend this only for macro definitions. In ordinary code,
replacing ";" with "," and if/else with "?:" will often (but not
always) merely obfuscate the code with no increase in performance.

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <* <http://users.sdsc.edu/~kst>
"We must do something. This is something. Therefore, we must do this."
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