Re: equality operator question
On May 5, 3:28 pm, p...@informatimago.com (Pascal J. Bourguignon)
James Kanze <james.ka...@gmail.com> writes:
On May 5, 4:40 am, "barcaroller" <barcarol...@music.net> wrote:
Is it now common practice to use conditional statements like
if (0 == i)
if (-1 == i)
if (true == i)
if (5 == i)
over the more traditional statements like
if (i == 0)
if (i == -1)
if (i == true)
if (i == 5)
for all types of 'i' (PODs and classes)?
No. First of all, you never compare with true or false. As for
the others, I'd say that it is generally universal practice to
put the constant to the right of the comparision operator. I
don't know where this practice originated, but it certainly
predates C++, and there's no reason to do otherwise in C++.
The reason is that if you have a normal keyboard, without rebound,
if (i = -1) ...
and then the compilers won't complain and will generate:
First, of course, I won't generally type that; I'll type:
if ( i == -1 ) ...
(with lot's of white space, so it's easy to see what each token
is). Second, if I do slip up, most compilers will warn, and of
course, the code will never get through code review, nor pass
any of the unit tests. So it's not really a big thing.
On the other hand, if you write:
if (-1 = i) ...
since -1 is not a LHS, -1=i is invalid and the compilers will
signal an error.
Which only works if you're comparing with a constant. On the
other hand, if I write:
if ( f() == x ) ...
if ( x == f() ) ...
I get the added check with the more natural form. So you force
an unnatural form to occasionally get the check, and more often
to not get it when you otherwise would.
However, I cannot say that's it's common practice.
I prefer to write if(i==-1)...
and I just insert a grep in my makefiles to catch any
assignment in if, while or do conditionals.
Automated code review:-). Definitely a good idea.
James Kanze (GABI Software) email:firstname.lastname@example.org
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