«

Stefan pointed you the C way with vsnprintf. Since you seem to use C++ you
should maybe ask also in a C++ newsgroup. There is a stringstream class. But
I am not expirienced with that.

On 29/06/2012 15:05, Andrej Viktorovich wrote:
> Thank you, I got many answers to a lot of hypothetical questions.

No - you got the answer to the question you asked. You were told why
your example code failed and you were shown a number of ways in which,
using C, your code could be made to work.

> But how do you deal in case for example when you need just log some
> variables like debug info.

That is not the question you asked. The answer to it is probably
language-specific. If you are actually planning to work in C, you'ld use
a member of the printf family - your example below suggests that
fprintf() may be appropriate.

In C++ it is likely that there are other mechanisms which would be
appropriate.

If you are planning to use C++, you should post your questions to the
appropriate newsgroup - comp.lang.c++

>
> void SaveToDebugInfoFile(char[] info)
> {
> ...
> }
>
> int main
> {
> int a =1;
> int b =2;
> int c =3;
> ...
>
> SaveToDebugInfoFile(*/ need to pass a,b,c variables with some text /*);
> }
>
> I hope to have in output something like this:
> "variable a=1 , variable b=2, variable c=3"
>
>
> int main
> {
> int a =1;
> int b =2;
> int c =3;
> ...
>
> SaveToDebugInfoFile(*/ need to pass a,b,c variables with some text /*);
> }
>
> I hope to have in output something like this:
> "variable a=1 , variable b=2, variable c=3"
>

בת×�ריך יו×� שישי, 29 ביו×*×™ 2012 15:05:39 UTC+1, מ×�ת Andrej Viktorovich:
> Thank you, I got many answers to a lot of hypothetical questions.
>
> But how do you deal in case for example when you need just log some variables like debug info. How you construct string that will be saved to file? Do you really make such long and boring conversion to string routine (creating char[] variable, calling itoa ) for each variable of a,b,c and then concatenate them into one string before passing to function SaveToDebugInfoFile.
>
>
No, you use vsprintf to construct

SaveToDebugInfoFilef(char *format, ...)

Then you just pass strings to this function, exactly as you would to printf().

If you want to dump an array there's no way of doing it other than in a loop. You could write your own vsprintf() equivalent that takes arrays, but that would probably be more trouble than its worth.

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New halftoning routines

Andrej Viktorovich <> writes:
>> Assuming that C++ differs little from C in this respect, you're
>> returning the address of a buffer which is local to the invocation of
>> intToStr. It's not a good idea.
>
> I have feeling that in C i must create memory area and pass it like
> parameter to function that converts int to string.
>
> But I would like to have simple function with one param of integer and
> I would like to ask intToString to do all that job of creating memory
> area and I need just char[] on utput. Is it possible to think that way
> in C?

Yes, but you have to think *really hard*. }

You can't just return a string or array from a C function. It has to be
allocated somewhere, and you pretty much have to manage that allocation
yourself.

There are (at least) three approaches:

1. Declare the local buffer as "static", so its lifetime extends over
the entire execution of the program. This has some drawbacks. There's
only one buffer in memory, so successive calls will clobber the value
from previous calls. And you have to decide how big the buffer needs to
be.

2. Have the caller pass in a pointer to (the first element of) its own
buffer.

3. Have the function allocate a new buffer using malloc(). This makes
the caller responsible for free()ing the buffer when it's done with it.

(Since you're using "cout << ...", you might consider using C++
mechanisms for this, like std::string. But if you have any questions
about C++, you'll need to ask in comp.lang.c++.)

--
Keith Thompson (The_Other_Keith) kst- <http://www.ghoti.net/~kst>
Will write code for food.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"

On Friday, June 29, 2012 7:05:39 AM UTC-7, Andrej Viktorovich wrote:
> Thank you, I got many answers to a lot of hypothetical questions.
>
> But how do you deal in case for example when you need just log some variables like debug info. How you construct string that will be saved to file? Do you really make such long and boring conversion to string routine (creating char[] variable, calling itoa ) for each variable of a,b,c and then concatenate them into one string before passing to function SaveToDebugInfoFile.
>
> void SaveToDebugInfoFile(char[] info)
> {
> ...
> }
>
> int main
> {
> int a =1;
> int b =2;
> int c =3;
> ...
>
> SaveToDebugInfoFile(*/ need to pass a,b,c variables with some text /*);
> }
>
> I hope to have in output something like this:
> "variable a=1 , variable b=2, variable c=3"
>
>
> int main
> {
> int a =1;
> int b =2;
> int c =3;
> ...
>
> SaveToDebugInfoFile(*/ need to pass a,b,c variables with some text /*);
> }
>
> I hope to have in output something like this:
> "variable a=1 , variable b=2, variable c=3"

If all you want is to write it to a log file, what's wrong
with just using fprintf() ? Then you don't ever need to
create buffer space at all.

On 2012-06-29, James Kuyper <> wrote:
> cout << 55 << "\n";
>
> It would also be more idiomatic to use endl rather than "\n".

It's not the same thing. "\n" outputs a newline,
std::endl output a newline and performs a flush.

On Sun, 1 Jul 2012 21:26:20 +0000 (UTC), Ike Naar
<> wrote:

>On 2012-06-29, James Kuyper <> wrote:
>> cout << 55 << "\n";
>>
>> It would also be more idiomatic to use endl rather than "\n".
>
>It's not the same thing. "\n" outputs a newline,
>std::endl output a newline and performs a flush.

This actually works in a C program???

--
Remove del for email

On 2012-07-01, Barry Schwarz <> wrote:
> On Sun, 1 Jul 2012 21:26:20 +0000 (UTC), Ike Naar
><> wrote:
>
>>On 2012-06-29, James Kuyper <> wrote:
>>> cout << 55 << "\n";
>>>
>>> It would also be more idiomatic to use endl rather than "\n".
>>
>>It's not the same thing. "\n" outputs a newline,
>>std::endl output a newline and performs a flush.
>
> This actually works in a C program???

Well, it works in the dialect called C/C++

On 07/01/2012 05:31 PM, Barry Schwarz wrote:
> On Sun, 1 Jul 2012 21:26:20 +0000 (UTC), Ike Naar
> <> wrote:
>
>> On 2012-06-29, James Kuyper <> wrote:

[Restored context:]
>>> I thought you said you were using C? This looks like C++, a different,
>>> though closely related language. You'll get better answers about such
>>> things by going to comp.lang.c++. ... Also, do you realize
>>> that you'd get a similar result by writing

....
>>> cout << 55 << "\n";
>>>
>>> It would also be more idiomatic to use endl rather than "\n".
>>
>> It's not the same thing. "\n" outputs a newline,
>> std::endl output a newline and performs a flush.
>
> This actually works in a C program???

No, it was a comment referring to C++ code, as you can tell from the
restored context quoted above.

On 07/ 2/12 10:22 AM, James Kuyper wrote:
> On 07/01/2012 05:31 PM, Barry Schwarz wrote:
>> On Sun, 1 Jul 2012 21:26:20 +0000 (UTC), Ike Naar
>> <> wrote:
>>
>>> On 2012-06-29, James Kuyper<> wrote:
>
> [Restored context:]
>>>> I thought you said you were using C? This looks like C++, a different,
>>>> though closely related language. You'll get better answers about such
>>>> things by going to comp.lang.c++. ... Also, do you realize
>>>> that you'd get a similar result by writing
>
> ....
>>>> cout<< 55<< "\n";
>>>>
>>>> It would also be more idiomatic to use endl rather than "\n".
>>>
>>> It's not the same thing. "\n" outputs a newline,
>>> std::endl output a newline and performs a flush.
>>
>> This actually works in a C program???
>
> No, it was a comment referring to C++ code, as you can tell from the
> restored context quoted above.

Sense of humour MIA?

--
Ian Collins