PHP functions, arrays, strings and objects

Functions, arrays, strings and objects in PHP are the four most commonly used data types in development. Let’s talk about it briefly today PHPFunction, array, string object. In PHP development, this data type must be known.

Function

PHP functions are actually the same as JS functions

Use function to define a new function, followed by the name of the function. Then there is the function code

But you can use var in JS to define an anonymous function, but PHP cannot do this

The parameters passed in the PHP function are all You need to add the $ prefix, and you can't add anything like JS. Among the default values ​​​​of parameters, PHP directly assigns the default value to the parameter in () of the positioning parameter. This is still the same as JS. The same

One difference between PHP and JS is that PHP can use & to pass references

In fact, this is also very simple, just use parameters to pass in the variables of the code, the code As follows:

functiondisplay(&$text) {  
$text .= "say hello.;  
}   
$my ="good, "  
display($my)  
echo $my//good, say hello.

Another thing is different from JS, but the same thing as Python is that include and require

Generally there is only one global scope in JS, so for different JS files , it is difficult to communicate (also because communication between JS is generally achieved through different js files with different scripts in HTML, but due to the existence of same-origin security restrictions, it is difficult for js to communicate between different files) )

But PHP, like python, can easily communicate with different files. Python uses import

, while PHP has two types, one is include and the other is require. The effect is also very obvious. include refers to inclusion, that is, the code can be run regardless of whether it is included or not, but require must contain the require code to run the subsequent code

String

It’s the same as JS, you need to escape \\, or it’s a built-in function for string operations

, the idea is the same, when you need to use these functions Let’s look for it

Array

PHP arrays are the same as JS arrays. The types of array elements can also be inconsistent, and each element can be used array[index] to get

. But when creating an array, PHP is different from JS. When using index to create an array, you can use the following method to create

$myArray = array(0=>1, 1=>2, 2=>3). There is no need to add a new in front of the array here like JS. In (), index is used to create elements. What is used is =>, which is not available in JS.

array_splice

The function can delete elements in the array

array_solice($myArray, 4) The first parameter is the array, and the second parameter is index.

Array traversal

, the one used in JS is

for (keyin array)

, while the one used in PHP is foreach($myArrayas $key => $value) It can also be foreach($myArrayas $value)

Of course it is still a function that operates on the array, this part is omitted

Object

Like most languages, PHP also includes classes, objects, polymorphism, methods, properties, inheritance and encapsulation

$this->

Variable name

To reference the relevant attributes of the internally visible class

Public, protected and private

The default is public public can be set to private private or protected

The get and set accessors are the same as those of JS

The above is all the content of this article. I hope it will be helpful to new PHP programmers~

Related recommendations:

The basic structure of PHP functions

The most complete introduction to PHP arrays

The most complete PHP string processing function

PHP object instantiation singleton method

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