In this post we will take a look and another new operator in PHP 7. This operator is the Combined Comparison or Spaceship operator (<=>). This operator is a three way comparison operator. It will do greater-than, less-than and equal comparisons between two operands.
The spaceship operator (<=>) returns -1 if the left side is smaller, 0 if the values are equal and 1 if the left side is larger. It can be used on all generic PHP values with the same semantics as < , <=, ==, >=, >. This operator is similar in behavior to strcmp() or version_compare(). This operator can be used with integers, floats, strings, arrays, objects, etc.
Example usage:
$c = $a <=> $b; // This is equivalent to $c = ($a < $b) ? -1 : (($a > $b) ? 1 : 0);
Here are a few more examples from PHP RFP for Combined Comparison (Spaceship) Operator
// Integers echo 1 <=> 1; // 0 echo 1 <=> 2; // -1 echo 2 <=> 1; // 1 // Floats echo 1.5 <=> 1.5; // 0 echo 1.5 <=> 2.5; // -1 echo 2.5 <=> 1.5; // 1 // Strings echo "a" <=> "a"; // 0 echo "a" <=> "b"; // -1 echo "b" <=> "a"; // 1 echo "a" <=> "aa"; // -1 echo "zz" <=> "aa"; // 1 // Arrays echo [] <=> []; // 0 echo [1, 2, 3] <=> [1, 2, 3]; // 0 echo [1, 2, 3] <=> []; // 1 echo [1, 2, 3] <=> [1, 2, 1]; // 1 echo [1, 2, 3] <=> [1, 2, 4]; // -1 // Objects $a = (object) ["a" => "<span class="hiddenGrammarError" pre=""><span class="hiddenGrammarError" pre="">b"]; $b</span></span> = (object) ["a" => "b"]; echo $a <=> $b; // 0 $a = (object) ["a" => "b"]; $b = (object) ["a" => "c"]; echo $a <=> $b; // -1 $a = (object) ["a" => "c"]; $b = (object) ["a" => "b"]; echo $a <=> $b; // 1 // only values are compared $a = (object) ["a" => "b"]; $b = (object) ["b" => "b"]; echo $a <=> $b; // 0
More reading:
PHP RFP for Combined Comparison (Spaceship) Operator