PHP: Testing whether three variables are equal

Question

I've never come across this before, but how would you test whether three variables are the same? The following, obviously doesn't work but I can't think of an elegant (and correct) way to write the following:

if ($select_above_average === $select_average === $select_below_average) { }

Answer 1

if ((a == b) && (b == c)) {
   ... they're all equal ...
}

by the transitive relation

Answer 2

$values = array($select_above_average, $select_average, $select_below_average);

if(count(array_unique($values)) === 1) {
    // do stuff if all elements are the same
}

Would be another way to do it.

Answer 3

if ($select_above_average === $select_average
    && $select_average === $select_below_average) { }

Answer 4

you already have your answer by Adam but a good way to remember how to do this correctly is to remember for a single validation you should be wrapping in () braces, if your only doing one single check then you already have the braces provided by the if ( ) statement.

Example:

if ( a === b )

and if your doing multiple then

if( ( a === b ) && ( c === d ) )

Sop if you remember that every set of braces is a validation check, you can have login like this:

if( (( a === b ) || ( c === d )) && ( e === f ) )

if statements and many other logical operations work on hierarchy so that the amount of individual checks within a check has an effect on he parent check.

taking the third example above if a === b or c === d fails then e === f will never be checked as the ab,cd is wrapped in braces so that is returned and checked.

Hope this helps you a little more.