Re: A question about '=='' in C++!

On Sep 21, 10:15 am, "Guofu Chen" <gc...@[EMAIL PROTECTED]
> wrote:
> Can anyone tell me the different between
> (1)
> int i, j;
> i = j ==1;
> cout << i;
> cout << j;
>
> and
> (2)
> int i, j;
> i = j = 1;
> cout << i;
> cout << j;
>

Look up operator precedence and associativity in your favourite
textbook.  i = j == 1 is the same as i = (j == 1), which will assign 0
to i if j is not equal to 1, and will assign 1 if j is equal to 1.  On
the other hand, i = j = 1 is the same as i = (j = 1), which assigns 1
to j and then assigns the value of (j=1), which is the new value of j,
to i.

Note the following problems with your code snippets, btw:

- you have not initialized j in the first snippet.  You must
initialize your variables before reading from them.

- the "cout <<" statements appear to be C++.  I'm only answering your
question here because it has essentially nothing to do with C++.  In
future, please direct C++ queries to the comp.lang.c++ newsgroup.

> Why the result of  (1) is
>
> 0 0
>
> while the result of (2) is
>
> 1 1
>

HTH.

--
Kushal
-- 
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