I've been thus far unable to find this information in the official PHP docs, or on this site. So, that may mean I'm searching under the wrong terms, or it is not supported. What am I looking for? I'll describe it...
Let's say I have the following comparisons in PHP:
if (($a == $b) && ($b == $c))
doSomething();
else
doSomethingElse();
if (($d < $e) && ($e < $f))
doSomething();
else
doSomethingElse();
Does PHP have some kind of syntax to chain the comparisons together without the explicit AND-ing of two different comparisons? For example, is something like this possible:
if ($a == $b == $c)
doSomething();
else
doSomethingElse();
if ($d < $e < $f)
doSomething();
else
doSomethingElse();
Note that I am looking for a syntactic shorthand in the language. I know that I can easily write a function for each of these chained comparisons, but this is a kludgy work-around, and not desired. For example:
function chainedGreaterThan($args)
{
for ($i = 0; $i < count($args) - 1; $i++)
if ($args[$i] <= $args[$i + 1])
return false;
return true;
}
This technically would work, but is not a syntactic shorthand given by the language.
Chaining with the comparison operator == returns True only if all values are equal. If there is even one different value, False is returned. Be careful when using the comparison operator != that returns True when the values are not equivalent.
The chaining of operators can be written as follows: if a < b < c : {.....} According to associativity and precedence in Python, all comparison operations in Python have the same priority, which is lower than that of any arithmetic, shifting or bitwise operation.
Python supports chaining of comparison operators, which means if we wanted to find out if b lies between a and c we can do a < b < c , making code super-intuitive. Python evaluates such expressions like how we do in mathematics. which means a < b < c is evaluated as (a < b) and (b < c) .
No, PHP doesn't have anything like this.
You could do something awful like this when you have very large amounts of things to compare.
<?php
$arr = [1, 2, 3];
$less_than = function($a, $b) {
return $a < $b;
};
$greater_than = function($a, $b) {
return $a > $b;
};
function apply_operator($arr, $operator) {
for ($i = 0; $i < sizeof($arr) - 1; $i++) {
if (!$operator($arr[$i], $arr[$i + 1])) {
return false;
}
}
return true;
}
var_dump(apply_operator($arr, $less_than)); // true
var_dump(apply_operator($arr, $greater_than)); // false
But for greater/less than you can just sort and compare to the original, and for equal you can check the size of array_unique
.
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