Posted by Erwin Moller on 11/06/06 16:06

brett wrote:

>> if ((is_page()) || ($category->cat_ID === $cat) ) {
>
> What is the notation for equivalency? Is it "==" or "==="?

== is more loose than ===

=== also checks if the data compared is of the same type.
eg

$a = 1;
$b = "1";
if ($a == $b){
// evaluates to true
}

if ($a === $b){
// evaluates to false
}

This can be a very important extra = in some situations. :-)

A common situation where === makes sense is a functioncall that can return 0
as valid answer, eg:

// This function returns the number of elements in an array
// or it returns false if not an array is passed
function countNumber($someArray){
if is_array($someArray){
return count($someArray);
} else {
return false;
}
}

Now if you use this function and feed the following 3 variables to it:
$test = array("bla",3,24);
$result = countNumber($test);
if ($result){
echo "number of elements $result";
} else {
echo "Not an array!";
}

That works ok, it returns 3.

suppose $test was:
$test = 23;

Which is also ok, it would respond that $test is not an array.

Now the problem:
$test = array();

If you feed this, PHP will correctly count 0 elements, and thus return 0.

However, when used as an expression, 0 evaluates to false, thus PHP will
incorrectly say it was not an array.

If you use the following construct, this will NOT happen.

if ($result === true){
echo "number of elements $result";
} else {
echo "Not an array!";
}


Regards,
Erwin Moller


>
> Thanks,
> Brett

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