indentation

[Bill Cunningham]

I have had several complaints by some people who wish to help me and I
wish to get the problem straight. I wrote this small utility myself and
added some indentation and I wonder if it is acceptable. It does make source
easier to read.

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv) {
if (argc!=3) {
fprintf(stderr, "usage error\n");
return -1;
}
double x,y;
x=strtod(argv[1],NULL);
y=strtod(argv[2],NULL);
printf("%.2f\n" ,y/x);
return 0;
}

Is this a good example of a properly indended program?

Bill

[Mark McIntyre]

Bill Cunningham wrote:

"Joe Wright" <jo********@com cast.netwrote in message
news:xd******** *************** *******@comcast .com...

>..given your program as input. What do you think?

The first copy of the file I wrote has had its indentation changed by
the news server or client. It was indented when I posted it and the
indentation was removed. Maybe nntp does that. The progran was originally
indented like this.

if (argc!3) {
fprintf(stderr, "usage error\n");
return -1;
}

This is one of many possible styles. The main thing is to use
intentation to identify each block, and to use a consistent style.

The two commonest are probable

if (x)
{
bodyhere();
}

and
if (x) {
bodyhere();
}

The one you used above is less common in my experience.

[Nick Keighley]

On 8 May, 01:51, "Bill Cunningham" <nos...@nspam.c omwrote:

* * I have had several complaints by some people who wish to help me
and I wish to get the problem straight. I wrote this small utility
myself and added some indentation and I wonder if it is acceptable.
It does make source easier to read.

that's the idea! :-)

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv) {
*if (argc!=3) {
* fprintf(stderr, "usage error\n");
* return -1;
* }
*double x,y;
*x=strtod(argv[1],NULL);
*y=strtod(argv[2],NULL);
*printf("%.2f\n ",y/x);
*return 0;
*}

* * Is this a good example of a properly indended program?

well it's better! In fact it's good enough to prevent
me whining about indentation. Personnally I prefer the
braces to line up, but the above is ok. I definitly
prefer whitespace around binary operators (eg. =)
and I'd use more blank lines. But on usenet saving vertical
space can be a good thing.

#include <stdio.h>
#include <stdlib.h>

int main (int argc, char **argv)
{
double x;
double y;

if (argc != 3)
{
fprintf (stderr,"usage error\n");
return -1;
}

x = strtod (argv [1], NULL);
y = strtod (argv [2], NULL);

printf ("%.2f\n", y / x);

return 0;
}

the main thing is to group things together that
logically belong together, leave enough whitespace
(horizontal and vertical) to aid readability and
above all, be consistent.

Oh, and never use tabs!

[mutter, one project had a standard of 4 column indent
and 8 space tabs. So you mixed tabs and spaces. eek!]
--
Nick Keighley

"The Real Programmer wants a "you asked for it, you got it"
text editor--complicated, cryptic, powerful, unforgiving,
dangerous. TECO, to be precise."

[pereges]

i use tabs for eg.

void func1(void)
{
...

[brix99luftballons]

Richard Heathfield ha scritto:

cr88192 said:

<snip>

>now, I usually code in notepad,

Oh dear. :-)

Oh dear dear :-)

>which has inflexible 8-space tabs, so
usually I use this.
if the tab space is adjustable, usually I like 4 space tabs.

And IMO 3 is too many. Vive la difference!

You forgot <stdio.h>
You meant argc.

A type , may be...

If argc is 0, the behaviour is undefined. If it is >= 1, argv[0] must
represent the program name in some way, but need not be a string
representing the invocation name for the program. It could even be a pid!

argc must be 1 (the program name ia always passed as argument), by
standard.
But, yes, it is best to check it...

> return(-1);

This has no portable meaning (and the parentheses are redundantly
superfluous).

I'm not agree, it' more readable.

>>
fd=fopen(argv[1], "rb");
...
return(0);

Again, the parentheses are superfluously redundant.

Question of style: for me it is better to place parentesis around the
returned value.
What about an horrible return like this one ????
return a*32 / b + c - d * e / oh_my_good ;

0 is fine - it means success.

Ok, it's a standard value

A -1 return value has no de jure meaning in C (which is, at least, in
keeping with the better kinds of tradition - if we knew why we did them,
they wouldn't be traditions!).

To indicate failure portably, use EXIT_FAILURE.

:-)

brix

[pete]

brix99luftballo ns wrote:

argc must be 1 (the program name ia always passed as argument), by
standard.

No. argc may be zero.

N869
5.1.2.2.1 Program startup

[#2] If they are declared, the parameters to the main
function shall obey the following constraints:

-- The value of argc shall be nonnegative.

-- argv[argc] shall be a null pointer.

-- If the value of argc is greater than zero, the array
members argv[0] through argv[argc-1] inclusive shall
contain pointers to strings, which are given
implementation-defined values by the host environment
prior to program startup. The intent is to supply to
the program information determined prior to program
startup from elsewhere in the hosted environment. If
the host environment is not capable of supplying
strings with letters in both uppercase and lowercase,
the implementation shall ensure that the strings are
received in lowercase.

-- If the value of argc is greater than zero, the string
pointed to by argv[0] represents the program name;
argv[0][0] shall be the null character if the program
name is not available from the host environment. If
the value of argc is greater than one, the strings
pointed to by argv[1] through argv[argc-1] represent
the program parameters.

--
pete

[Richard Heathfield]

brix99luftballo ns said:

>

Richard Heathfield ha scritto:

<snip>

>If argc is 0, the behaviour is undefined. If it is >= 1, argv[0] must
represent the program name in some way, but need not be a string
representing the invocation name for the program. It could even be a
pid!

argc must be 1 (the program name ia always passed as argument), by
standard.

Wrong.

But, yes, it is best to check it...

Right, so let's do that. See 2.1.2.2 of C89 or 5.1.2.2.1 of C99:

* The value of argc shall be nonnegative.

* argv[argc] shall be a null pointer.

* If the value of argc is greater than zero, the array members
argv[0] through argv[argc-1] inclusive shall contain pointers to
strings, which are given implementation-defined values by the host
environment prior to program startup. The intent is to supply to the
program information determined prior to program startup from elsewhere
in the hosted environment. [...]

It is clear from the above that argc may be 0.

>> return(-1);

This has no portable meaning (and the parentheses are redundantly
superfluous) .

I'm not agree, it' more readable.

Please explain why parentheses make the return code more readable. Does
this apply to every expression, or just to the expression that
(optionally) follows a return statement? If so, why is return special?

>> fd=fopen(argv[1], "rb");
...
return(0);

Again, the parentheses are superfluously redundant.

Question of style: for me it is better to place parentesis around the
returned value.
What about an horrible return like this one ????
return a*32 / b + c - d * e / oh_my_good ;

What makes you think that adding parentheses helps? If the reader can't
comprehend a*32 / b + c - d * e / oh_my_good, why are they more likely to
comprehend (a*32 / b + c - d * e / oh_my_good)?

<snip>

--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999

[rio]

"Joe Wright" <jo********@com cast.netha scritto nel messaggio
news:xd******** *************** *******@comcast .com...

Bill Cunningham wrote:

> I have had several complaints by some people who wish to help me and
I wish to get the problem straight. I wrote this small utility myself and
added some indentation and I wonder if it is acceptable. It does make
source easier to read.

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv) {
if (argc!=3) {
fprintf(stderr, "usage error\n");
return -1;
}
double x,y;
x=strtod(argv[1],NULL);
y=strtod(argv[2],NULL);
printf("%.2f\n" ,y/x);
return 0;
}

Is this a good example of a properly indended program?

>Bill

i like below

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv)
{double x, y;

if (argc!=3) { fprintf(stderr, "usage error\n"); return -1;}

x=strtod(argv[1], 0);
y=strtod(argv[2], 0);

return (x!=0.0) ?
(printf("%.2f\n ", y/x), 0): (printf("Error: x==0\n"), -1) ;
}

[Eligiusz Narutowicz]

Bart <[e-mail] rites:

On May 8, 11:33Â*am, "cr88192" <cr88...@NOSPAM .hotmail.comwro te:

>"Richard Heathfield" <[e-mail].i nvalidwrote in message

news:HM******* *************** ********@bt.com ...

cr88192 said:

<snip>

>now, I usually code in notepad,

Oh dear. :-)

all in all it is a good and simple editor...

(So you can write some very complex software but not an editor better
than notepad?..)

If you like notepad, you might like to try qed.exe, if you can still
find it. (I think an updated version here http://www.movsd.com/qed.htm).
It has some useful indent commands. And I believe still smaller than
notepad.

Anyone using notepad to write C should be fired. There are lots of
productivity tools which make programming more sure fire and certainly
easier - not to use at least some of them is silly.

[Flash Gordon]

cr88192 wrote:

"Richard Heathfield" <rj*@see.sig.in validwrote in message
news:HM******** *************** *******@bt.com. ..

>cr88192 said:

<snip>

>> {
printf("usage: %s <filename>\n" , argv[0]);

If argc is 0, the behaviour is undefined. If it is >= 1, argv[0] must
represent the program name in some way, but need not be a string
representing the invocation name for the program. It could even be a pid!

this is a common practice though, and also I don't personally know of any OS
where argc is not at least 1...

<snip>

Any Unix if the exec* call used to invoke the program provides a
parameter list with argv[0]=NULL. In Unix programs other than your shell
are allowed to exec your program, so you cannot guarantee you will get a
program name.

>>but 0 and -1 are more common/traditional.

A -1 return value has no de jure meaning in C (which is, at least, in
keeping with the better kinds of tradition - if we knew why we did them,
they wouldn't be traditions!).

To indicate failure portably, use EXIT_FAILURE.

it is more correct, but -1 is a very common value for indicating error as
well.
I think usually any value other than 0 counts as an error.

<snip>

Not on VMS. IIRC on VMS odd return values indicate success and even
return values indicate failure with the C compiler using some magic to
make returning 0 actually return an odd number to the environment.

There *are* good reasons for using non-C-standard return values from
main, but in my experience they only apply when you have return return
values indicating something more than simple success/failure.
--
Flash Gordon

[Richard Heathfield]

Flash Gordon said:

cr88192 wrote:

<snip>

>I don't personally know of
any OS where argc is not at least 1...

Always a shaky argument.

>
<snip>

Any Unix if the exec* call used to invoke the program provides a
parameter list with argv[0]=NULL.

Right. Also, I believe, older Mac systems.

<snip>
--
Richard Heathfield <http://www.cpax.org.uk >
Email: -http://www. +rjh@
Google users: <http://www.cpax.org.uk/prg/writings/googly.php>
"Usenet is a strange place" - dmr 29 July 1999