PHP 7 Scalar type declarations and return type declarations

What is a Scalar type declarations?
Allowing/Not-Allowing datatype declaration in functions is known as Scalar type declarations.


Question: What are different types of Scalar type declarations?
1) Coercive Mode (default)
2) Strict Mode


What are different type of data-type can be used in Scalar type declarations?

1. int
2. float
3. bool
4. string
5. interfaces
6. array
7. callable

Question: Give the examples of Scalar type declarations with Coercive Mode (default)
Example 1

$a=1; // integer
$b=2; //integer
function FunctionName1(int $a, int $b){
return $a + $b;
}
echo FunctionName1($a, $b); //3

Example 2

   function sum(int ...$ints) {
      return array_sum($ints);
   }

   print(sum(3, '2', 5.1)); //10

Example 3

function FunctionName3(int $a, int $b){
return $a * $b;
}

echo FunctionName3('hello', 10); //PHP Fatal error: Uncaught TypeError: Argument 1 passed to FunctionName() must be of the type integer, string given.

Example 4

$a='1One'; 
$b=2; //integer
function FunctionName3(int $a, int $b){
return $a + $b;
}
echo FunctionName3($a, $b);//RESULT: PHP Notice: A non well formed numeric value encountered on line 5

Question: Give the examples of Scalar type declarations with STRICT MODE?
Example 1

declare(strict_types=1); 

$a=1; // integer
$b=2; //integer
function phpFunction (int $a, int $b){
return $a + $b;
}

echo phpFunction1($a, $b);//3

Example 2

declare(strict_types=1); 

$a='1'; // String
$b=2; //integer
function phpFunction1 (int $a, int $b){
return $a + $b;
}

echo phpFunction1($a, $b);//Fatal error: Uncaught TypeError: Argument 1 passed to phpFunction1() must be of the type int, string given

Question: Give the examples of Return type declarations with STRICT MODE?
Example 1

$a='10'; //  string
$b=2; // integer
function phpFunctionReturn ($a, $b) : int  {
return $a * $b;
}
echo phpFunctionReturn ($a, $b);

Example 2

declare(strict_types=1); 
$a='10'; //  string
$b=2; // integer
function phpFunctionReturn ($a, $b) : string  {
return $a * $b;
}
echo phpFunctionReturn ($a, $b);//PHP Fatal error:  Uncaught TypeError: Return value of phpFunctionReturn() must be of the type string, integer returned in /home/cg/root/7035270/main.php:6