printf doubt

[dutche]

Hi, there is some kind of difference in these two statements?

float num = 154.87;
printf("There is : $0.0f",num);


and


float num = 154.87;
printf("There is : $f",num);

[Richard Heathfield]

Re: printf doubt

dutche said:

Hi, there is some kind of difference in these two statements?
>
float num = 154.87;
printf("There is : $0.0f",num);
>
>
and
>
>
float num = 154.87;
printf("There is : $f",num);

Yes. (We will assume that the '$' character is in the execution character
set.)

The first of your examples will print:

There is : $0.0f

The second will print:

There is : $f

These are different outputs.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999

http://www.cpax.org.uk

email: rjh at above domain (but drop the www, obviously)

[dutche]

Re: printf doubt


Richard Heathfield escreveu:

dutche said:
>

Hi, there is some kind of difference in these two statements?

float num = 154.87;
printf("There is : $0.0f",num);


and


float num = 154.87;
printf("There is : $f",num);

>
Yes. (We will assume that the '$' character is in the execution character
set.)
>
The first of your examples will print:
>
There is : $0.0f
>
The second will print:
>
There is : $f
>
These are different outputs.
>
--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999

http://www.cpax.org.uk

email: rjh at above domain (but drop the www, obviously)

Sorry I made a mistake :)

float num = 154.87;
printf("There is : $%0.0f",num);

and

float num = 154.87;
printf("There is : $%f",num);

[Andrew Poelstra]

Re: printf doubt

On 2006-07-11, dutche <dutche@gmail.c omwrote:

Hi, there is some kind of difference in these two statements?
>
float num = 154.87;
printf("There is : $0.0f",num);
>
>
and
>
>
float num = 154.87;
printf("There is : $f",num);
>

Run them, and you'll note that one will print "There is : $0.0f" and
other other will print "There is : $f", neither of which will have a
newline*

* Actually, on a lot of systems it won't print at all, because you're
missing a newline.

You need to read a good beginner's C book.

--
Andrew Poelstra <http://www.wpsoftware. net/projects/>
To email me, use "apoelstra" at the above domain.
"You people hate mathematics." -- James Harris

[Richard Heathfield]

Re: printf doubt

dutche said:

<snip>

>
float num = 154.87;
printf("There is : $%0.0f",num);

This will print the value in at least 0 (first 0!) columns but possibly
more, and with a precision of 0 (second 0) decimal places. The number is
"rounded to the appropriate number of digits", as the Standard puts it. So
in this case it'll display 155 (because that's closer than 154).

and
>
float num = 154.87;
printf("There is : $%f",num);

This will just print the value, to default precision. On my implementation
it gives 154.869995 as the result.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999

http://www.cpax.org.uk

email: rjh at above domain (but drop the www, obviously)

[Andrew Poelstra]

Re: printf doubt

On 2006-07-11, Andrew Poelstra <apoelstra@loca lhost.localdoma inwrote:

On 2006-07-11, dutche <dutche@gmail.c omwrote:

>Hi, there is some kind of difference in these two statements?
>>
>float num = 154.87;
>printf("Ther e is : $0.0f",num);

>
You need to read a good beginner's C book.
>

Never mind; I thought you confused `$' and `%', but according to your
other post, you just forgot to type `%', which is an understandable
mistake (because the characters are right beside each other on a US
keyboard, and you'd already typed one).

--
Andrew Poelstra <http://www.wpsoftware. net/projects/>
To email me, use "apoelstra" at the above domain.
"You people hate mathematics." -- James Harris

[Robert Gamble]

Re: printf doubt

Richard Heathfield wrote:

dutche said:
>
<snip>

float num = 154.87;
printf("There is : $%0.0f",num);

>
This will print the value in at least 0 (first 0!) columns but possibly
more, and with a precision of 0 (second 0) decimal places. The number is
"rounded to the appropriate number of digits", as the Standard puts it. So
in this case it'll display 155 (because that's closer than 154).
>

and

float num = 154.87;
printf("There is : $%f",num);

>
This will just print the value, to default precision.

More precisely, it will print the value as if a precision of 6 had been
specified (ignoring the fact that no newline is present).

Robert Gamble

[Fred Kleinschmidt]

Re: printf doubt


"dutche" <dutche@gmail.c omwrote in message
news:1152626834 .778040.179400@ h48g2000cwc.goo glegroups.com.. .

Hi, there is some kind of difference in these two statements?
>
float num = 154.87;
printf("There is : $0.0f",num);
>
>
and
>
>
float num = 154.87;
printf("There is : $f",num);
>

Yes. The first one will print:
There is : $0.0f
and the second will print:
There is : $f

And without a newline, it is possible that neither will show up.
--
Fred L. Kleinschmidt
Boeing Associate Technical Fellow
Technical Architect, Software Reuse Project

[Barry Schwarz]

Re: printf doubt

On Tue, 11 Jul 2006 14:14:55 +0000, Richard Heathfield
<invalid@invali d.invalidwrote:

>dutche said:
>

>Hi, there is some kind of difference in these two statements?
>>
>float num = 154.87;
>printf("Ther e is : $0.0f",num);
>>
>>
>and
>>
>>
>float num = 154.87;
>printf("Ther e is : $f",num);

>
>Yes. (We will assume that the '$' character is in the execution character
>set.)
>
>The first of your examples will print:
>
>There is : $0.0f
>
>The second will print:
>
>There is : $f
>
>These are different outputs.

Does not the presence of a superfluous argument lead to undefined
behavior?


Remove del for email

[Ben Pfaff]

Re: printf doubt

Barry Schwarz <schwarzb@doezl .netwrites:

Does not the presence of a superfluous argument lead to undefined
behavior?

No. From C99 7.19.6.1 "The fprintf function":

If the format is exhausted while arguments remain, the
excess arguments are evaluated (as always) but are otherwise
ignored.
--
"You call this a *C* question? What the hell are you smoking?" --Kaz

[Richard Heathfield]

Re: printf doubt

Barry Schwarz said:

<snip>

>
Does not the presence of a superfluous argument lead to undefined
behavior?

No. The relevant C89 draft wording is:

"If the format is exhausted while arguments remain, the excess
arguments are evaluated (as always) but are otherwise ignored."

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999

http://www.cpax.org.uk

email: rjh at above domain (but drop the www, obviously)

[Chris Torek]

Re: printf doubt

In article <SvWdnfxfb-xyKC7ZRVnyvA@bt .com>
Richard Heathfield <invalid@invali d.invalidwrote:

>dutche said:

>float num = 154.87;
>printf("Ther e is : $%0.0f",num);

>This will print the value in at least 0 (first 0!) columns ...

Aha, a rare Richard Heathfield error! :-)

In a printf conversion, the "0" character is a *flag*, not a field
width, unless:

- you are already working on a field width, or
- you are already working on a precision

(and possibly if you use various extensions as well). For instance,

printf("%040d\n ", 12);

prints "00000000000000 000000000000000 00000000012\n", while:

printf ("%40d\n", 12);

prints " 12\n".

A zero flag is allowed with %f conversions, with the obvious meaning
(so printing 0.5 with %012.6f produces "00000.5000 00"; note that the
field width includes the decimal-point character).

>but possibly more, and with a precision of 0 (second 0) decimal
>places.

Note that, for %f format, if no precision is specified, a default
value of 6 is assumed. So:

printf("%f\n", val);

and:

printf("%.6f\n" , val);

have identical meanings.
--
In-Real-Life: Chris Torek, Wind River Systems
Salt Lake City, UT, USA (40°39.22'N, 111°50.29'W) +1 801 277 2603
email: forget about it http://web.torek.net/torek/index.html
Reading email is like searching for food in the garbage, thanks to spammers.

[Keith Thompson]

Re: printf doubt

Andrew Poelstra <apoelstra@loca lhost.localdoma inwrites:

On 2006-07-11, dutche <dutche@gmail.c omwrote:

>Hi, there is some kind of difference in these two statements?
>>
>float num = 154.87;
>printf("Ther e is : $0.0f",num);
>>
>>
>and
>>
>>
>float num = 154.87;
>printf("Ther e is : $f",num);
>>

>
Run them, and you'll note that one will print "There is : $0.0f" and
other other will print "There is : $f", neither of which will have a
newline*
>
* Actually, on a lot of systems it won't print at all, because you're
missing a newline.

Actually, we don't know that he's missing a newline. He's only showed
us a couple of small code fragments, not an entire program. If
putchar('\n') or equivalent is executed later on, he's fine (at least
as far as trailing newlines are concerned).

--
Keith Thompson (The_Other_Keit h) kst-u@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.

[Flash Gordon]

Re: printf doubt

Barry Schwarz wrote:

On Tue, 11 Jul 2006 14:14:55 +0000, Richard Heathfield
<invalid@invali d.invalidwrote:
>

>dutche said:
>>

>>Hi, there is some kind of difference in these two statements?
>>>
>>float num = 154.87;
>>printf("The re is : $0.0f",num);

<snip>

Does not the presence of a superfluous argument lead to undefined
behavior?

No, you are explicitly allowed to pass extra arguments to printf. The
standard states "If the format is exhausted while arguments remain, the
excess arguments are evaluated (as always) but are otherwise ignored."
--
Flash Gordon, living in interesting times.
Web site - http://home.flash-gordon.me.uk/
comp.lang.c posting guidelines and intro:

http://clc-wiki.net/wiki/Intro_to_clc

[Richard Heathfield]

Re: printf doubt

Chris Torek said:

In article <SvWdnfxfb-xyKC7ZRVnyvA@bt .com>
Richard Heathfield <invalid@invali d.invalidwrote:

>>dutche said:

>>float num = 154.87;
>>printf("The re is : $%0.0f",num);

>

>>This will print the value in at least 0 (first 0!) columns ...

>
Aha, a rare Richard Heathfield error! :-)

I don't know whether to be annoyed or delighted. :-)

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999

http://www.cpax.org.uk

email: rjh at above domain (but drop the www, obviously)