Learn PHP

Learn Artifact: PhpStudy a key to set up the PHP environment

grammar:

PHP is a scripting language that can be nested in an HTML page

Nested HTML file:
```
<!DOCTYPE html>
<html>
    <head>
        <title>PHP</title>
    </head>
    <body>
      <?php
          // php代码;
      ?>
    </body>
</html>
```
PHP also can be saved to a separate "* .php" file and is accessed but in php file, it must be "<?" At the beginning "?>" End! php code will only be parsed and executed here
PHP is case sensitive identification
PHP supports three mainstream Notes: double slash "#" sign, multi-line comments

variable:

Variable rules:

Variables begin with $ symbol
Variable names must begin with a letter or an underscore, numbers, letters, underscores the variable name
PHP process does not create a command variable name, variable assignment process is created

Scope:

local (local): Only allows statements to access their own grammatical structure (internal function declaration)
global (overall): Allows access to the current statement in all the grammatical structure of PHP programs (outside the function declaration)

Access global variables:

global keyword is used within the function to access global variables inside the function to access the global variables must use the global keyword before the visit.
```
<?php
    $x = 5 ; 
  $y = 10 ; 
  function myTest(){
        global $x , $y ;
        $y = $x + $y ;
    }
  myTest();
  echo $y ;
?>
```
static (static): implementation of the outcome variable, the next round is not reset

Static access:

When variable declaration, add static statement, you can not reset the change in number of visits and the variable variable
```
<?php
    function myTest(){
    static $x = 0 ; 
    echo $x ; 
    $x ++ ; 
  }
  myTest();
  myTest();
  myTest();
?>
```

Output:

echo output:

May output more than one string

<?php 
    echo '<p>Hello,World!</p>';
 ?>

print output:

type of data:

String:

String is a sequence of characters, the text string within the quotation marks belong

Integer:

No decimal number combinations (including negative)

Float:

All combinations of numbers is not an integer, and scientific notation

Boolean logic:

true and false

Array:

A variable value stored in one or more of

Creating an array using the keyword "array"

<?php
    $cars = array ("HUAWEI","China","GO!")s
    var_dump($cars);//返回数组的类型和值
?>
    // 运行结果
// “array(3) { [0]=> string(6) "HUAWEI" [1]=> string(5) "China" [2]=> string(3) "GO!" }”

Keywords: var_dump Returns size of the array, the data type of each parameter value and other information

Object:

Using the "class" keyword to declare object data types

<?php
    class Car {
    var $color ; 
    function Car($color = "green") {
        $this -> color = $color;
    }
    function what_color(){
        return $this->color;
    }
  }
?>

NULL values:

Represents a variable to a null value (the value set to null, empty the representative variable values)

Analyzing Data type:

var_dump ():

Type and value of the variable print
Syntax: void var_dump (mixed $ expression)
No return value

iS function:

is_bool (): Boolean value determines whether
is_float (): determines whether the float
is_int (): determining whether an integer
is_numeric (): determines whether numeric
is_string (): determining whether a string
is_array (): determining whether an array
is_object (): whether the object is determined
is_null (): determines whether null
is_resource (): determine whether the resource type

isset()：

Check the variable exists
Returns: Returns true variable exists

empty()：

Check if the argument is null (isset () may only detect the presence or absence)
Returns: present and non-empty variable returns false (var = null was considered empty)

PHP system constants:

System constants	Explanation
__ FILE __	PHP file name
__ LINE __	PHP program current line number
PHP_VERSION	PHP version number
PHP_OS	Operating system name
TRUE	true
FALSE	false
E_ERROR	The most recent error
E_WARNING	Recent warnings
E_PARSE	Resolve potential problems with grammar
E_NOTICE	Unusual error

Operator:

Arithmetic operators:

// + - * / % ++ --

Arithmetic addition from the mold decrementing

String operators:

String concatenation operator: . (Dot)

Connecting equal: = (equal points)

Assignment operator:

Assignment: =

Less like: - =

Et plus: + =

Multiplication and other: * =

In addition other: / =

I like to take:% =

Comparison operators:

Greater than, less than, greater than or equal, less than equal to, equal to, not equal to

Full equal to: ===

Insufficiency:! ==

Logical Operators:

Logical AND: and &&

Logical OR: or ||

Logic Non-: not!

Ternary operator:

Conditional operator: ? :

Control structures:

if the branch condition:

slightly

Switch conditional statement:

slightly

While cycle:

slightly

do ... while loop:

slightly

for loop:

slightly

Control functions:

略（break/continue）

Delivery values: *

:( assignment pass both different memory addresses)

$a = $b ;

Assignment by reference :( two variables the same address)

$a = &$b ;

Array:

Array type:

Enumerated array: Index subscript is an integer
Associative array: string superscript index
Multidimensional array: array element is an array

Create an array:

Keywords: Array () creates an array
Identifier:
- $arr[key] = value ;
- $arr[] = value ;

Array functions:

print_r (): print variable information

unset (): delete array element

foreach (): traverse the array elements

array_shift()：

The first cell array was removed and returned as a result

array_pop():

The last element of the array cell and returns removed

array_unshift()：

In an array of one or more elements prepend

array_push()：

Insertion of one or more elements to the end of the array

array_values():

Returns an array of all the values and the establishment of a numeric index

count (): calculated value of the number of attributes

array_sum (): calculated value and

array_reverse (): returns an array of reverse

list (): the array element assigned to the variable

<?php 
    $IntArray = array(2,5,9,13,7,9,21,7,9,24,38) ;
    $MAX = $IntArray[0];
    $MIN = $IntArray[0];
    $MAX_i = $MIN_i = 0;
    for ($i=0; $i < count($IntArray) ; $i++) { 
        if ($MAX < $IntArray[$i]) {
            $MAX = $IntArray[$i] ; 
            $MAX_i = $i ;
        }
        if ($MIN > $IntArray[$i]) {
            $MIN = $IntArray[$i] ;
            $MIN_i = $i ; 
        }
    }
    echo "Array_MAX:".$MAX."<br />MAX_i=".$MAX_i ;
    echo "<br /><br />";
    echo "Array_MIN:".$MIN."<br />MIN_i=".$MIN_i ;
    echo "<hr />";
    // 位置交换
    echo "位置交换前：".print_r($IntArray) ; 
    $M = $IntArray[$MIN_i] ;
    $IntArray[$MIN_i] = $IntArray[$MAX_i] ; 
    $IntArray[$MAX_i] = $M ;
    echo "<br />";
    echo "位置交换后：".print_r($IntArray) ;
    echo "<hr />";
    // 反转数组
    echo print_r(array_reverse($IntArray));
 ?>

Superglobals :

Elements / Code	description
$_SERVER['PHP_SELF']	Returns the file name of the script execution.
$_SERVER['GATEWAY_INTERFACE']	Returns the CGI specification used by the server version.
$_SERVER['SERVER_ADDR']	Returns the current IP address of the server running the script is located.
$_SERVER['SERVER_NAME']	Returns the host name of the server currently running script is located (for example www.w3school.com.cn).
$_SERVER['SERVER_SOFTWARE']	Returns a string identifying the server (such as Apache / 2.2.24).
$_SERVER['SERVER_PROTOCOL']	Name and version (e.g., "HTTP / 1.0") communications protocol return the requested page.
$_SERVER['REQUEST_METHOD']	The method used to access the page return request (e.g. POST).
$_SERVER['REQUEST_TIME']	Returns the timestamp of the start request (e.g., 1577687494).
$_SERVER['QUERY_STRING']	Returns the query string, if it is to access this page via the query string.
$_SERVER['HTTP_ACCEPT']	Returns the current request from the request header.
$_SERVER['HTTP_ACCEPT_CHARSET']	Accept_Charset head returns from the current request (e.g. utf-8, ISO-8859-1)
$_SERVER['HTTP_HOST']	Host head returns from the current request.
$_SERVER['HTTP_REFERER']	Returns the current page full URL (unreliable because not all user agents are supported).
$_SERVER['HTTPS']	Whether through secure HTTP protocol query script.
$_SERVER['REMOTE_ADDR']	Back to Browse user's IP address of the current page.
$_SERVER['REMOTE_HOST']	Returns the host name of the user browsing the current page.
$_SERVER['REMOTE_PORT']	Back on the user machine connected to the port number used by the Web server.
$_SERVER['SCRIPT_FILENAME']	Returns the absolute path of the currently executing script.
$_SERVER['SERVER_ADMIN']	This value indicates the SERVER_ADMIN Apache server configuration file.
$_SERVER['SERVER_PORT']	Port Web server. The default value is "80."
$_SERVER['SERVER_SIGNATURE']	返回服务器版本和虚拟主机名。
$_SERVER['PATH_TRANSLATED']	当前脚本所在文件系统（非文档根目录）的基本路径。
$_SERVER['SCRIPT_NAME']	返回当前脚本的路径。
$_SERVER['SCRIPT_URI']	返回当前页面的 URI。

函数：

关键字：function name() { …… }

函数参数：

值传递参数：

在函数调用的时候，允许传递参数值给函数，函数可以自由使用参数进行操作

引用传递参数：

如果希望函数可以修改参数值，可以使用引用参数进行传递

引用传递，只需要在参数前加上 “&” 符号就可以

$arr = array(1,2,3,4);
function addElement(&$arr){
    $arr[count($arr)] = 100;
    print_r($arr);   //在函数内输出$arr
}
addElement($arr);
print_r($arr);  //在函数外输出

默认值传递：

function hobby($who,$style=‘运动’){
    echo “$who 喜欢 $style”;
}
hobby(“张三”,“唱歌”);
hobby(“张三”);

global关键字：

引用函数外部的参数（引用传递性质的参数）

$name = "Mary";//初始化变量
function getName(){
    global $name; //引入外部的变量
    echo "我的名字叫：$name";
}
getName();

内置函数：

echo语句：输出
print语句：输出
include语句：包含并运行指定文件
require语句：包含并运行指定文件

Learn PHP - Learn papers

Learn PHP

grammar:

variable:

Variable rules:

Scope:

Output:

echo output:

print output:

type of data:

String:

Integer:

Float:

Boolean logic:

Array:

Object:

NULL values:

Analyzing Data type:

var_dump ():

iS function:

isset()：

empty()：

PHP system constants:

Operator:

Arithmetic operators:

String operators:

Assignment operator:

Comparison operators:

Logical Operators:

Ternary operator:

Control structures:

if the branch condition:

Switch conditional statement:

While cycle:

do ... while loop:

for loop:

Control functions:

Delivery values: *

Array:

Array type:

Create an array:

Array functions:

print_r (): print variable information

unset (): delete array element

foreach (): traverse the array elements

array_shift()：

array_pop():

array_unshift()：

array_push()：

array_values():

count (): calculated value of the number of attributes

array_sum (): calculated value and

array_reverse (): returns an array of reverse

list (): the array element assigned to the variable

Superglobals :

函数：

函数参数：

内置函数：

Guess you like