Scalar type declaration basics in Php

• By Admin
• Jan 05, 2019

In Php, Scalar Type Declarations two different types options :

1. Coercive mode :  coercive mode is a default mode and need not to be specified.

EXAMPLE :: COERCIVE MODE

<?php

    function sum(int ...$ints)
    {
       return array_sum($ints);
    }
    
    print "<pre>";
    print_r(sum(2,3,4));
    print"</pre>";

?>

------------ ****** ------------

OUTPUT:
         9

2. Strict mode : Strict mode need to be explicitly type hinted.

There are number of functions parameters can be forced to using modes.

1  int
2  float
3  Boolean
4  string
5  interface
6  array
7  callable

Example 1:

<?php

        declare(strict_types = 1);
        
        function add(int ...$ints)
        {
           return array_sum($ints);
        }
            
        print "<pre>";
        print_r(add('string',3,4,5,7,8,10));  // throw an error
        print "</pre>";

?>

In above example  if we pass a string in add function then it will throw an error because of strict mode.

It will throws an error like this :

( ! ) Fatal error: Uncaught TypeError: Argument 1 passed to add() must be of the type integer, string given, called in D:\PHP1\wamp\www\wordpress\Basics\ScalarTypeDeclaration\std.php on line 39 and defined in D:\PHP1\wamp\www\wordpress\Basics\ScalarTypeDeclaration\std.php on line 35.

Example 2: ( strict mode in class )

<?php

        declare(strict_types =1);
        
        class A
        {
            public $a;
            public $b;
            public $c;
            
            public function add(int $a,int $b,int $c) : int
            {
               return $c = $a+$b+$c;
            }
        }
        
        $obj = new A();
        echo $obj->add(1,20,30);

?>

------------ ****** ------------

OUTPUT:
         51

In above example if we pass a string in add function then it will throws an error.

<?php

		declare(strict_types =1);
		
		class A{
		
			public $a;
			public $b;
			public $c;
			
			public function add(int $a,int $b,int $c) : int{
			    return $c = $a+$b+$c;
			}
		}
		
		$obj = new A();
		echo $obj->add(1,20,"scalar type declaration example" );
		
?>

Fatal error: Uncaught TypeError: Argument 3 passed to A::add() must be of the type integer, string given, called in D:\PHP1\wamp\www\wordpress\Basics\ScalarTypeDeclaration\std.php on line 53 and defined in D:\PHP1\wamp\www\wordpress\Basics\ScalarTypeDeclaration\std.php on line 47

Example 3:

<?php

		declare(strict_types=1);
		
		class A{
		
			public $str ="Scalar Type Declaration";
			
			public function show_method() : string{
			    return $this->str;
			}
		}
		
		$obj = new A();
		echo $obj->show_method();
		
?>

------------ ****** ------------

OUTPUT:
         Scalar Type Declaration.