PHP 7 - Scalar Type Declarations

In PHP 7, a new feature, Scalar type declarations, has been introduced. Scalar type declaration has two options −

• coercive − coercive is default mode and need not to be specified.

• strict − strict mode has to explicitly hinted.

Following types for function parameters can be enforced using the above modes −

• int
• float
• bool
• string
• interfaces
• array
• callable

Example - Coercive Mode

<?php
   // Coercive mode
   function sum(int ...$ints) {
      return array_sum($ints);
   }
   print(sum(2, '3', 4.1));
?>

It produces the following browser output −

9

Example - Strict Mode

<?php
   // Strict mode
   declare(strict_types = 1);
   function sum(int ...$ints) {
      return array_sum($ints);
   }
   print(sum(2, '3', 4.1));
?>

It produces the following browser output −

Fatal error: Uncaught TypeError: Argument 2 passed to sum() must be of the type integer, string given, ...