«

On Thu, 22 Jan 2004 13:05:00 +0200, "nfg" <> wrote:

>Is there a way to comment out part of a format string used in i.e. printf,
>sprintf, etc? What I have in mind is a statement like printf("%s %s %s",
>string1, string2, string3), and the temporary need to eliminate one format
>specifier (%s) and its corresponding string: printf("%s %s /* %s */",
>string1, string2, /*string3*/). Now, while coomenting out string3 works
>fine, obviously the comment delimiters /* and */ around %s do not get
>accepted as such. Workarounds, anyone?
>
If the comment string is a literal as in your example, then the answer
is no because you are not allowed to modify a string literal at any
time. If you change it to
char format[] = "%s %s %s";
printf(format, string1, string2, string3);
you could then later say
memcpy(format, " ", 2);
printf(format, string1 string2);
or even
memcpy(format, "%d", 2);
printf(format, int1, string1 string2);

Let the off topic record reflect that this will go a long way to
making your code extremely difficult to understand or maintain. To
put it another way, it really sucks.


<<Remove the del for email>>
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Barry Schwarz wrote:

> On Thu, 22 Jan 2004 13:05:00 +0200, "nfg" <> wrote:
>
>
>>Is there a way to comment out part of a format string used in i.e. printf,
>>sprintf, etc? What I have in mind is a statement like printf("%s %s %s",
>>string1, string2, string3), and the temporary need to eliminate one format
>>specifier (%s) and its corresponding string: printf("%s %s /* %s */",
>>string1, string2, /*string3*/). Now, while coomenting out string3 works
>>fine, obviously the comment delimiters /* and */ around %s do not get
>>accepted as such. Workarounds, anyone?
>>
>
> If the comment string is a literal as in your example, then the answer
> is no because you are not allowed to modify a string literal at any
> time. If you change it to
> char format[] = "%s %s %s";
> printf(format, string1, string2, string3);
> you could then later say
> memcpy(format, " ", 2);
> printf(format, string1 string2);
> or even
> memcpy(format, "%d", 2);
> printf(format, int1, string1 string2);
>
> Let the off topic record reflect that this will go a long way to
> making your code extremely difficult to understand or maintain. To
> put it another way, it really sucks.

An alternative relies on string concatenation:

printf("%s" " %s" " %s", string1, string2, string3);
printf("%s"/*" %s"*/" %s", string1,/*string2,*/string3);

I'd think I'd prefer:

printf("%s", string1);
printf(" %s", string2);
printf(" %s", string3);

You can then simply comment out the middle call.

(Oh - the original question omitted string3; mea culpa, mutatis
mutandis, or thereabouts).

--
Jonathan Leffler #include <disclaimer.h>
Email: ,
Guardian of DBD::Informix v2003.04 -- http://dbi.perl.org/
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"Barry Schwarz" <> wrote in message
news:clcm-20040122-...
> On Thu, 22 Jan 2004 13:05:00 +0200, "nfg" <>
wrote:
>
> >Is there a way to comment out part of a format string used in i.e.
printf,
> >sprintf, etc? What I have in mind is a statement like printf("%s %s
%s",
> >string1, string2, string3), and the temporary need to eliminate one
format
> >specifier (%s) and its corresponding string: printf("%s %s /* %s
*/",
> >string1, string2, /*string3*/). Now, while coomenting out string3
works
> >fine, obviously the comment delimiters /* and */ around %s do not
get
> >accepted as such. Workarounds, anyone?

One way to comment out parts of string literals is to rely on implicit
string literal concatenation:

const char* s = "In the country of Westphalia, "
"in the castle of the most noble "
"Baron of Thunder-ten-tronckh, " // Who's he?
// "lived a youth whom Nature had "
"endowed with a most sweet "
"disposition.";

If you arrange your string literal appropriately, you can conviently
comment parts out, and add comments to parts if they require
explanation. I'd only recommend this in rare cases, however, such as
with very complex regular expressions.

Jonathan
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"nfg" <> wrote:

> Is there a way to comment out part of a format string used in i.e.
> printf, sprintf, etc? What I have in mind is a statement like
> printf("%s %s %s", string1, string2, string3), and the temporary
> need to eliminate one format specifier (%s) and its corresponding
> string: printf("%s %s /* %s */", string1, string2, /*string3*/).
> Now, while coomenting out string3 works fine, obviously the
> comment delimiters /* and */ around %s do not get accepted as
> such. Workarounds, anyone?

Maybe you could write:

printf("%s" " %s" "%s", s1, s2, s3);

and remove s2 by:

printf("%s" /*" %s"*/ "%s", s1, /*s2,*/ s3);

taking advantage of string concatenation.

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In <clcm-20040122-> Barry Schwarz <> writes:

>On Thu, 22 Jan 2004 13:05:00 +0200, "nfg" <> wrote:
>
>>Is there a way to comment out part of a format string used in i.e. printf,
>>sprintf, etc? What I have in mind is a statement like printf("%s %s %s",
>>string1, string2, string3), and the temporary need to eliminate one format
>>specifier (%s) and its corresponding string: printf("%s %s /* %s */",
>>string1, string2, /*string3*/). Now, while coomenting out string3 works
>>fine, obviously the comment delimiters /* and */ around %s do not get
>>accepted as such. Workarounds, anyone?
>>
>If the comment string is a literal as in your example, then the answer
>is no because you are not allowed to modify a string literal at any
>time.

Note that he doesn't want to do it at run time and there is nothing wrong
in modifying a string literal with a text editor

The solution is ugly, but it is possible:

printf("%s %s " /* "%s" */, string1, string2 /*, string3*/);

It works because comments get replaced by white space in TP3, while
adjacent string literal splicing occurs in TP6. To uncomment it, it is
enough to remove the /* and */.

I would comment out the whole printf call, though:

/* printf("%s %s %s", string1, string2, string3); */
printf("%s %s ", string1, string2);

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email:
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On 23 Jan 2004 05:19:15 GMT, Barry Schwarz <> wrote:

>On Thu, 22 Jan 2004 13:05:00 +0200, "nfg" <> wrote:
>
>>Is there a way to comment out part of a format string used in i.e. printf,
>>sprintf, etc? What I have in mind is a statement like printf("%s %s %s",
>>string1, string2, string3), and the temporary need to eliminate one format
>>specifier (%s) and its corresponding string: printf("%s %s /* %s */",
>>string1, string2, /*string3*/). Now, while coomenting out string3 works
>>fine, obviously the comment delimiters /* and */ around %s do not get
>>accepted as such. Workarounds, anyone?
>>
>If the comment string is a literal as in your example, then the answer
>is no because you are not allowed to modify a string literal at any
>time. If you change it to

You could do something like this:

printf("%s " "%s " "%s", string1, string2, string3);
printf("%s " "%s " /*"%s"*/, string1, string2 /*, string3*/);

If you want to avoid getting lost in the quotes, you might try
something like

#define STR "%s "

printf(STR STR STR, string1, string2, string3);
printf(STR STR /*STR*/, string1, string2 /*, string3*/);

though that may be overkill. Regards,

-=Dave
--
Change is inevitable, progress is not.
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Barry Schwarz wrote:
> On Thu, 22 Jan 2004 13:05:00 +0200, "nfg" <> wrote:
>
>
>>Is there a way to comment out part of a format string used in i.e. printf,
>>sprintf, etc? What I have in mind is a statement like printf("%s %s %s",
>>string1, string2, string3), and the temporary need to eliminate one format
>>specifier (%s) and its corresponding string: printf("%s %s /* %s */",
>>string1, string2, /*string3*/). Now, while coomenting out string3 works
>>fine, obviously the comment delimiters /* and */ around %s do not get
>>accepted as such. Workarounds, anyone?
>>
>
> If the comment string is a literal as in your example, then the answer
> is no because you are not allowed to modify a string literal at any
> time. If you change it to
> char format[] = "%s %s %s";
> printf(format, string1, string2, string3);
> you could then later say
> memcpy(format, " ", 2);
> printf(format, string1 string2);
> or even
> memcpy(format, "%d", 2);
> printf(format, int1, string1 string2);
>
> Let the off topic record reflect that this will go a long way to
> making your code extremely difficult to understand or maintain. To
> put it another way, it really sucks.
>
>
> <<Remove the del for email>>
The other approach is to break up the format string (using implicit
cnocatenation). For example:

printf("%s "
"%s "
"%s "
,string1, string2 ,string3);

This way you can comment out whichever piece you want.

HTH,
--ag

--
Artie Gold -- Austin, Texas
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Barry Schwarz <> wrote in message news:<clcm-20040122->...
> On Thu, 22 Jan 2004 13:05:00 +0200, "nfg" <> wrote:
>
> >Is there a way to comment out part of a format string used in i.e. printf,
> >sprintf, etc? What I have in mind is a statement like printf("%s %s %s",
> >string1, string2, string3), and the temporary need to eliminate one format
> >specifier (%s) and its corresponding string: printf("%s %s /* %s */",
> >string1, string2, /*string3*/). Now, while coomenting out string3 works
> >fine, obviously the comment delimiters /* and */ around %s do not get
> >accepted as such. Workarounds, anyone?
> >
> If the comment string is a literal as in your example, then the answer
> is no because you are not allowed to modify a string literal at any
> time. If you change it to
> char format[] = "%s %s %s";
> printf(format, string1, string2, string3);
> you could then later say
> memcpy(format, " ", 2);
> printf(format, string1 string2);
> or even
> memcpy(format, "%d", 2);
> printf(format, int1, string1 string2);
>
> Let the off topic record reflect that this will go a long way to
> making your code extremely difficult to understand or maintain. To
> put it another way, it really sucks.


It's ugly, but since C pastes together adjacent string in the source
code, this will work:

printf("%s %s" /* "%s "*/, string1, string2, /*string3*/)
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"Jonathan Leffler" <> wrote in message
news:clcm-20040123-...
> Barry Schwarz wrote:
>
> > On Thu, 22 Jan 2004 13:05:00 +0200, "nfg" <> wrote:
> >
> >
> >>Is there a way to comment out part of a format string used in i.e.
printf,
> >>sprintf, etc? What I have in mind is a statement like printf("%s %s %s",
> >>string1, string2, string3), and the temporary need to eliminate one
format
> >>specifier (%s) and its corresponding string: printf("%s %s /* %s */",
> >>string1, string2, /*string3*/). Now, while coomenting out string3 works
> >>fine, obviously the comment delimiters /* and */ around %s do not get
> >>accepted as such. Workarounds, anyone?

I have a sorta OT question about this thread. Since I am teaching C++,
should I ever get into the use of sprintf, printf, etc. or are these
included in C++ because they occur in C? (I suspect I know the answer.)
Is this post then not OT in comp.lang.c++ and should be deleted from that
ng?
Or am I being provincial?
--
Gary

Barry Schwarz wrote:

> On Thu, 22 Jan 2004 13:05:00 +0200, "nfg" <> wrote:
>
>>Is there a way to comment out part of a format string used in i.e.
>>printf, sprintf, etc? What I have in mind is a statement like
>>printf("%s %s %s", string1, string2, string3), and the temporary need
>>to eliminate one format specifier (%s) and its corresponding string:
>>printf("%s %s /* %s */", string1, string2, /*string3*/). Now, while
>>coomenting out string3 works fine, obviously the comment delimiters /*
>>and */ around %s do not get accepted as such. Workarounds, anyone?
>>
> If the comment string is a literal as in your example, then the answer
> is no because you are not allowed to modify a string literal at any
> time. If you change it to
> char format[] = "%s %s %s";
> printf(format, string1, string2, string3);
> you could then later say
> memcpy(format, " ", 2);
> printf(format, string1 string2);
> or even
> memcpy(format, "%d", 2);
> printf(format, int1, string1 string2);
>
> Let the off topic record reflect that this will go a long way to
> making your code extremely difficult to understand or maintain. To
> put it another way, it really sucks.

Since this was posted to comp.lang.c++, I assume a C++ solution will
also do, so why not just use cout instead of printf?

cout << string1 << ' ' << string2 << ' ' << string3;

You can easily somment out one of the strings without the need to change
any format specifier.

[mod note: the crosspost was probably a bad idea. -mod]
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