Re: equality operator question

On Sun, 4 May 2008 22:40:28 -0400, "barcaroller"
<barcaroller@[EMAIL PROTECTED]
> wrote in comp.lang.c++:

> 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 cl*****)?

The reason for writing the constant first in an equality comparison is
quite simple.  A fairly common typographical error is type only one
'=' once in a while when two are intended, and needed.

Consider the implications of accidentally typing:

   if (i = 0)

....when you meant to type:

   if (i == 0)

Assuming a built-in type, or even a class type having an assignment
operator accepting an int, then the first version, the type, is not
only always false, but it also destroys the existing value of 'i'. Yet
it is syntactically correct and swallowed by the compiler without
complaint.

On the other hand, if you accidentally type "if (0 = i), the compiler
will emit a diagnostic and reject it.

So it is a very inexpensive method of catching a typing error on the
very first compile.  This is not an extremely common error, but is one
which happens to everyone once in a while.  And of course it doesn't
help when you are comparing two objects, but comparisons with a
constant are fairly frequent.

Some programmers consider it hideously ugly and refuse to ever use it.
I think it is useful and I use it.  It works, and it saves time when
you do happen to make that typo.

-- 
Jack Klein
Home: http://JK-Technology.Com
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