if (expression) check

[jamilur_rahman]

What is the BIG difference between checking the "if(expression) " in A
and B ? I'm used to with style A, "if(0==a)", but my peer reviewer
likes style B, how can I defend myself to stay with style A ?

style A:
....
....
int a = 1;
if(0==a)
{
/* Don't write my name */
}
....
....

style B:
....
....
int a = 1;
if(a==0)
{
/* Don't write my name */
}
....
....

[Stephen Hildrey]

ja************@ yahoo.com wrote:

What is the BIG difference between checking the "if(expression) " in A
and B ? I'm used to with style A, "if(0==a)", but my peer reviewer
likes style B, how can I defend myself to stay with style A ?

Personally, I prefer the "if (a == 0)" style - though I know some people
do like the "if (0 == a)" style because it reduces the chances of
assignment (rather than comparison) errors slipping through compilation.
I would explain that rationale to your peer reviewer.

Having said that, IMHO either is fine as long as you are consistent and
clear; without knowing your circumstances, it's hard to say whether your
reviewer has the right to disagree :-)

Steve
--
Stephen Hildrey
Mail: st***@uptime.or g.uk / Tel: [phone]
Jabber: st***@jabber.ea rth.li / MSN: fo*@hotmail.co. uk

[Eric Sosman]

ja************@ yahoo.com wrote:

What is the BIG difference between checking the "if(expression) " in A
and B ? I'm used to with style A, "if(0==a)", but my peer reviewer
likes style B, how can I defend myself to stay with style A ?

style A:
if(0==a)

style B:
if(a==0)

There is no "BIG" difference. People who like A say
it's protection against writing `=' instead of `=='. People
who like B say the mistake can be guarded against in ways
that are less ugly. I'm a B guy, myself, but don't consider
it a "BIG" deal.

As for defending yourself: Watch "Miss Congeniality"
and pay close attention when the protagonist demonstrates
what "SING" means.

--
Er*********@sun .com

[Michael Mair]

ja************@ yahoo.com wrote:

What is the BIG difference between checking the "if(expression) " in A
and B ? I'm used to with style A, "if(0==a)", but my peer reviewer
likes style B, how can I defend myself to stay with style A ?
<example snipped down to the essence:> style A:
....
if(0==a)

style B:
....
if(a==0)

The one "real advantage" of style A is that a forgotten second =
leads to a compile time error: 0=a does not compile, whereas a=0
does.
In the presence of compilers and tools like splint that can
warn you about stuff like this, this "advantage" is often
unnecessary. You can find any number of arguments about which
of the two is better in the archives of comp.lang.c. Most people
arguing against it are of the opinion that it is a "less natural"
way of writing the condition.

Personally, I like style B better but put up with A if coding
guidelines, conventions for a project, or similar prefer or
prescribe A.

In the absence of such conventions or standards, this is something
where everyone should be allowed to do as he or she likes --
everything else is mainly bullying of some sort in my eyes.
Cheers
Michael
--
E-Mail: Mine is an /at/ gmx /dot/ de address.

[Walter Roberson]

In article <11************ **********@o13g 2000cwo.googleg roups.com>,
<ja************ @yahoo.com> wrote:

What is the BIG difference between checking the "if(expression) " in A
and B ? I'm used to with style A, "if(0==a)", but my peer reviewer
likes style B, how can I defend myself to stay with style A ? style B: if(a==0)

Style A, 0==a, helps reduce problems in which an = is accidently
omitted. If you accidently wrote if(0=a) then the compiler would
complain.

If, though, following Style B you accidently wrote if(a=0)
then the statement is legal but with the undesired side-effect
of setting a to 0. Some compilers will warn about this, but this
is not a requirement and should not be counted on.

The trade-off is that a lot of people find it "unnatural" to
compare a constant to a variable: people tend to think of comparing
a variable to a constant, as in Style B.

There are some variations that might be acceptable, but they require
extra work that might be overlooked: e.g., if((int)a==0)
In this case, if you were to accidently write if((int)a=0)
then the compiler would complain because (int)a is not a modifiable
lvalue. Another form that works: if((a&a)==0) which has the advantage
of not having to know what the type of a is. Or perhaps
if(-a==0) since values do not change their relationship to 0 by
being negated (unless perhaps for an unsigned int on a 1's complement
machine??)
--
Look out, there are llamas!

[E. Robert Tisdale]

ja************@ yahoo.com wrote:

What is the BIG difference
between checking the "if(expression) " in A and B?
I'm used to with style A, "if (0 == a)",
but my peer reviewer likes style B.
How can I defend myself to stay with style A?
Tell your "peer reviewer" to kiss your ....
It's a matter of style.
You don't need to defend it.
style A:
....
....
const int a = 1;
if (0 == a) {
// Don't write my name.
}
....
....

style B:
....
....
const int a = 1;
if (a == 0) {
// Don't write my name.
}
....
....

[Mark B]

<ja************ @yahoo.com> wrote in message
news:11******** **************@ o13g2000cwo.goo glegroups.com.. .

What is the BIG difference between checking the "if(expression) " in A
and B ? I'm used to with style A, "if(0==a)", but my peer reviewer
likes style B, how can I defend myself to stay with style A ?

style A:
....
....
int a = 1;
if(0==a)
{
/* Don't write my name */
}
....
....

style B:
....
....
int a = 1;
if(a==0)
{
/* Don't write my name */
}

I personally prefer style B (not concerned with accidentally
making an assignment as I look at the code when I write it)
but the big defense is: hey, I'm an idiot and style A prevents
me from accidentally making an assignment and thus helps
prevent me from writing buggy code as I can count on the
compiler to catch all of my mistakes! :-)

If your reviewer is truly a peer... tell him that you don't give a
s**t about his personal preferences, style should not be an
issue in a code review. If that doesn't work, refer to the 'big
defense' in the previous paragraph and recite it verbatim.

Hope that helps,
Mark

[Default User]

Mark B wrote:

If your reviewer is truly a peer... tell him that you don't give a
s**t about his personal preferences, style should not be an
issue in a code review. If that doesn't work, refer to the 'big
defense' in the previous paragraph and recite it verbatim.

Around these parts, style is very much part of a peer review.
Programmers are required to write code in a consistent style because in
all likelyhood someone else will end up maintaining the code.


Brian

[Christian Bau]

In article <11************ **********@o13g 2000cwo.googleg roups.com>,
ja************@ yahoo.com wrote:

What is the BIG difference between checking the "if(expression) " in A
and B ? I'm used to with style A, "if(0==a)", but my peer reviewer
likes style B, how can I defend myself to stay with style A ?

style A:
....
....
int a = 1;
if(0==a)
{
/* Don't write my name */
}
....
....

style B:
....
....
int a = 1;
if(a==0)
{
/* Don't write my name */
}
....
....

Try replacing the "==" in "0==a" and "a==0" with a single "=".

The first style must produce an error when you make that change.

The second style with this change is correct C, but will produce a
warning on any C implementation that I would be willing to use. If it
doesn't produce warnings, find out how to turn warnings on in the
compiler. If you can't make the compiler produce a warning, get a
different compiler. If you can't get a different compiler, use style A,
otherwise use style B.

[Keith Thompson]

ja************@ yahoo.com writes:

What is the BIG difference between checking the "if(expression) " in A
and B ? I'm used to with style A, "if(0==a)", but my peer reviewer
likes style B, how can I defend myself to stay with style A ?

style A:
....
....
int a = 1;
if(0==a)
{
/* Don't write my name */
}
....
....

style B:
....
....
int a = 1;
if(a==0)
{
/* Don't write my name */
}
....
....

It is, as you say, a matter of style. That doesn't mean it's trivial,
it merely means that the compiler doesn't care which way you do it --
and the compiler is only one of the many entities that have to look at
your code.

My personal opinion is that the (0==a) form is jarring and ugly. If
it weren't for the possibility of typo-ing "=" rather than "==", there
would be absolutely no reason to use that form; I've never seen
comparisons written like that in languages that don't allow
assignments in expressions. I personally don't consider the risk of
an undetected typo so great that I'm willing to mangle my code like
that. If I really wanted to avoid confusing "=" and "==", I could
define macros ASSIGN and EQUAL_TO, and write a tool that would
complain about any direct use of the operators; the result would be
only slightly uglier than (0==a). (No, <iso646.h> doesn't provide
macros for either "=" or "==".)

But the above is, as I said, only my personal opinion (and a bit
overstated at that). I understand the argument in favor of (0==a),
and I understand that some people don't find it as jarring as I do.
Any competent C programmer should be able to read code using either
form, and any C compiler should generate equivalent (if not identical)
code for both.

Style is a legitimate subject for code reviews. If your work
environment imposes style guidelines that require one form or the
other, you should probably follow those guidelines. If it's a matter
of disagreement between you and a peer, then your opinion is as valid
as his (except, of course, that your peer is right because he agrees
with me).

Ultimately it's probably more of a political question than a language
question. You can expect a lot of opinions here, but I don't think
you can expect much help.

--
Keith Thompson (The_Other_Keit h) 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.