Hướng dẫn dùng prototypes definition trong PHP
Each function in the manual is documented for quick reference. Knowing how to read and understand the text will make learning PHP much easier. Rather than relying on examples or cut/paste, everyone should know how to read function definitions (prototypes). Let's begin:
Function definitions tell us what type of value is returned. Let's use the definition for strlen() as our first example: strlen (PHP 4, PHP 5, PHP 7) strlen -- Get string length Description strlen ( string $string ) : int Returns the length of given string.Explanation of a function definition
We could rewrite the above function definition in a generic way: function name ( parameter type parameter name ) : returned type Many functions take on multiple parameters, such as in_array(). Its prototype is as follows: in_array ( mixed $needle, array $haystack , bool $strict = false ) : bool What does this mean? in_array() returns a boolean value,
In addition the & (ampersand) symbol prepended to a function parameter allows the parameter to be passed by reference, as seen below: preg_match ( string $pattern , string $subject , array &$matches = null, int $flags = 0 , int $offset = 0 ) : int|false In this example, we can see the third optional parameter There are also functions with more complex PHP version information. Take html_entity_decode() as an example: (PHP 4 >= 4.3.0, PHP 5, PHP 7) This means that this function has only been available in a released version since PHP 4.3.0. There are no user contributed notes for this page. |