Creating a set of variables in PHP

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Creating a set of variables in PHP

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#1 by (3 votes)

2

I'm new to PHP, and I have some doubts. I noticed that when variables are created, the types are not specified.

Thus:

How do I create short, int, and char variables? Does it create the type of variable at startup of it?
And how could I check the size of the variable in bytes?
In addition, is it possible to create a set of variables in PHP, and from a identify of that set, assign values to those variables?

php

asked by anonymous 27.07.2015 / 15:59

1 answer

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score 3 · Accepted Answer

PHP is a weak typing language. This means that it is not necessary to set a type for the variable.

So it's like you said:

it creates the type of the variable at boot time

Example:

 $int = 1;

 $float = 1.44;

 $string = 'stackoverflow';

 $boolean = false;

 $array = array();

 $object = new stdClass;

You can test the types of these variables through functions like is_string , is_float , is_int and is_boolean .

You can also get the name of the variable type through the function gettype .

Example:

$array = array(1, 2, 3);

gettype($array); // array

Induction of Types

In PHP it is possible to "induce specific (not all) types" for parameters passed in functions.

We can check if a given object is a given instance or sub-instance. If it implements an interface, whether it is a callback, or if it is an array.

Type induction examples for classes:

class X{
   public function get(){}
}

function usa_x(X $x){
    return $x->get();
}

usa_x(new X);

Array type induction examples:

function usa_array(array $array){
  foreach($array as $key => $value);
}

usa_array(1); // gera um erro!

Type induction examples for callbacks (as of php 5.4):

function usa_callback(callable $callback)
{
     return $callback(1, 2, 3);
}
usa_callback('var_dump');

usa_callback(function ($a, $b, $c){
   var_dump($a, $b, $c);
});

usa_callback('nao_existe'); // gera um erro

SplType

There is an extension called Spl Type , where you can simulate type definition through instances of specific classes for each type.

Example:

$int = new SplInt(94);

try {
    $int = 'Try to cast a string value for fun';
} catch (UnexpectedValueException $uve) {
    echo $uve->getMessage() . PHP_EOL;
}

echo $int . PHP_EOL; // Value is not integer

If this is necessary (I think in most cases it is not), here is the link to SplType