PHP 备忘清单
===
这份 [PHP](https://www.php.net/manual/zh/index.php) 备忘单为快速查找最常用代码的正确语法提供了参考
入门
------
### hello.php
```php
<?php // 以 PHP 开放标签开头
echo "Hello World\n";
print("Hello quickref.me");
?>
```
PHP 运行命令
```shell
$ php hello.php
```
### 变量 Variables
```php
$boolean1 = true;
$boolean2 = True;
$int = 12;
$float = 3.1415926;
unset($float); // 删除变量
$str1 = "How are you?";
$str2 = 'Fine, thanks';
```
查看: [Types](#php-类型)
### 字符串 Strings
```php
$url = "quickref.me";
echo "I'm learning PHP at $url";
// 连接字符串
echo "I'm learning PHP at " . $url;
$hello = "Hello, ";
$hello .= "World!";
echo $hello; # => Hello, World!
```
查看: [Strings](#php-字符串)
### 数组 Arrays
```php
$num = [1, 3, 5, 7, 9];
$num[5] = 11;
unset($num[2]); // 删除变量
print_r($num); # => 1 3 7 9 11
echo count($num); # => 5
```
查看: [Arrays](#php-数组)
### 运算符 Operators
```php
$x = 1;
$y = 2;
$sum = $x + $y;
echo $sum; # => 3
```
查看: [Operators](#php-运算符)
### Include
<!--rehype:wrap-class=row-span-3-->
#### vars.php
```php
<?php // 以 PHP 开放标签开头。
$fruit = 'apple';
echo "I was imported";
return 'Anything you like.';
?>
```
#### test.php
```php
<?php
include 'vars.php';
echo $fruit . "\n"; # => apple
/* 与 include 相同，
如果不能包含则导致错误*/
require 'vars.php';
// 也有效
include('vars.php');
require('vars.php');
// 通过 HTTP 包含
include 'http://x.com/file.php';
// 包含和返回语句
$result = include 'vars.php';
echo $result; # => Anything you like.
?>
```
### 功能 Functions
```php
function add($num1, $num2 = 1) {
return $num1 + $num2;
}
echo add(10); # => 11
echo add(10, 5); # => 15
```
查看: [Functions](#php-函数)
### 注释 Comments
```php
# 这是一个单行 shell 样式的注释
// 这是一行 c++ 风格的注释
/* 这是一个多行注释
另一行注释 */
```
### 常数 Constants
```php
const MY_CONST = "hello";
echo MY_CONST; # => hello
# => MY_CONST is: hello
echo 'MY_CONST is: ' . MY_CONST;
```
### 类 Classes
```php
class Student {
public function __construct($name) {
$this->name = $name;
}
}
$alex = new Student("Alex");
```
查看: [Classes](#php-类)
PHP 类型
------
### 布尔值 Boolean
<!--rehype:wrap-class=row-span-2-->
```php
$boolean1 = true;
$boolean2 = TRUE;
$boolean3 = false;
$boolean4 = FALSE;
$boolean5 = (boolean) 1; # => true
$boolean6 = (boolean) 0; # => false
```
布尔值不区分大小写
### 整数 Integer
<!--rehype:wrap-class=row-span-2-->
```php
$int1 = 28; # => 28
$int2 = -32; # => -32
$int3 = 012; # => 10 (octal)
$int4 = 0x0F; # => 15 (hex)
$int5 = 0b101; # => 5 (binary)
# => 2000100000 (decimal, PHP 7.4.0)
$int6 = 2_000_100_000;
```
另见: [Integers](https://www.php.net/manual/en/language.types.integer.php)
### 字符串 Strings
```php
echo 'this is a simple string';
```
查看: [Strings](#php-字符串)
### 数组 Arrays
```php
$arr = array("hello", "world", "!");
```
查看: [Arrays](#php-数组)
### 浮点数 Float (Double)
```php
$float1 = 1.234;
$float2 = 1.2e7;
$float3 = 7E-10;
$float4 = 1_234.567; // as of PHP 7.4.0
var_dump($float4); // float(1234.567)
$float5 = 1 + "10.5"; # => 11.5
$float6 = 1 + "-1.3e3"; # => -1299
```
### Null
```php
$a = null;
$b = 'Hello php!';
echo $a ?? 'a is unset'; # => a is unset
echo $b ?? 'b is unset'; # => Hello php
$a = array();
$a == null # => true
$a === null # => false
is_null($a) # => false
```
### 可迭代对象 Iterables
```php
function bar(): iterable {
return [1, 2, 3];
}
function gen(): iterable {
yield 1;
yield 2;
yield 3;
}
foreach (bar() as $value) {
echo $value; # => 123
}
```
PHP 字符串
------
### 字符串 String
```php
# => '$String'
$sgl_quotes = '$String';
# => 'This is a $String.'
$dbl_quotes = "This is a $sgl_quotes.";
# => a tab character.
$escaped = "a \t tab character.";
# => a slash and a t: \t
$unescaped = 'a slash and a t: \t';
```
### 多行 Multi-line
```php
$str = "foo";
// 未插值的多行
$nowdoc = <<<'END'
Multi line string
$str
END;
// 将执行字符串插值
$heredoc = <<<END
Multi line
$str
END;
```
### 操作 Manipulation
```php
$s = "Hello Phper";
echo strlen($s); # => 11
echo substr($s, 0, 3); # => Hel
echo substr($s, 1); # => ello Phper
echo substr($s, -4, 3);# => hpe
echo strtoupper($s); # => HELLO PHPER
echo strtolower($s); # => hello phper
echo strpos($s, "l"); # => 2
var_dump(strpos($s, "L")); # => false
```
另见: [字符串函数](https://www.php.net/manual/en/ref.strings.php)
PHP 数组
------
### 定义
<!--rehype:wrap-class=row-span-2-->
```php
$a1 = ["hello", "world", "!"]
$a2 = array("hello", "world", "!");
$a3 = explode(",", "apple,pear,peach");
```
#### 混合 int 和 string 键
```php
$array = array(
"foo" => "bar",
"bar" => "foo",
100 => -100,
-100 => 100,
);
var_dump($array);
```
#### 短数组语法
```php
$array = [
"foo" => "bar",
"bar" => "foo",
];
```
### 多阵列
```php
$multiArray = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
print_r($multiArray[0][0]) # => 1
print_r($multiArray[0][1]) # => 2
print_r($multiArray[0][2]) # => 3
```
### 多类型
<!--rehype:wrap-class=row-span-2-->
```php
$array = array(
"foo" => "bar",
42 => 24,
"multi" => array(
"dim" => array(
"a" => "foo"
)
)
);
# => string(3) "bar"
var_dump($array["foo"]);
# => int(24)
var_dump($array[42]);
# => string(3) "foo"
var_dump($array["multi"]["dim"]["a"]);
```
### 操作
```php
$arr = array(5 => 1, 12 => 2);
$arr[] = 56; // 附加
$arr["x"] = 42; // 用键添加
sort($arr); // 排序
unset($arr[5]); // 消除
unset($arr); // 移除所有
```
查看: [数组函数](https://www.php.net/manual/en/ref.array.php)
### 索引迭代
```php
$array = array('a', 'b', 'c');
$count = count($array);
for ($i = 0; $i < $count; $i++) {
echo "i:{$i}, v:{$array[$i]}\n";
}
```
### 价值迭代
```php
$colors = array('red', 'blue', 'green');
foreach ($colors as $color) {
echo "Do you like $color?\n";
}
```
### 关键迭代
```php
$arr = ["foo" => "bar", "bar" => "foo"];
foreach ( $arr as $key => $value )
{
echo "key: " . $key . "\n";
echo "val: {$arr[$key]}\n";
}
```
### 串联阵列
```php
$a = [1, 2];
$b = [3, 4];
// PHP 7.4 以后
# => [1, 2, 3, 4]
$result = [...$a, ...$b];
```
### Into 函数
```php
$array = [1, 2];
function foo(int $a, int $b) {
echo $a; # => 1
echo $b; # => 2
}
foo(...$array);
```
### Splat运算符
```php
function foo($first, ...$other) {
var_dump($first); # => a
var_dump($other); # => ['b', 'c']
}
foo('a', 'b', 'c' /*, ...*/ );
// 或
function foo($first, string ...$other){}
```
PHP 运算符
-------
### 算术
:- | -
:- | -
`+` | 添加
`-` | 减法
`*` | 乘法
`/` | 分配
`%` | 取模
`**` | 求幂
### 分配
:- | -
:- | -
`a += b` | 如同 `a = a + b`
`a -= b` | 如同 `a = a – b`
`a *= b` | 如同 `a = a * b`
`a /= b` | 如同 `a = a / b`
`a %= b` | 如同 `a = a % b`
### 比较
:- | -
:- | -
`==` | 平等的
`===` | 完全相同的
`!=` | 不相等
`<>` | 不相等
`!==` | 不相同
`<` | 少于
`>` | 比...更棒
`<=` | 小于或等于
`>=` | 大于或等于
`<=>` | 小于/等于/大于
### 逻辑的
:- | -
:- | -
`and` | 和
`or` | 或者
`xor` | 独家或
`!` | 不是
`&&` | 和
`\|\|` | 或者
### 算术
```php
// 算术
$sum = 1 + 1; // 2
$difference = 2 - 1; // 1
$product = 2 * 2; // 4
$quotient = 2 / 1; // 2
// 速记算术
$num = 0;
$num += 1; // 将 $num 增加 1
echo $num++; // 打印 1（评估后的增量）
echo ++$num; // 打印 3（评估前的增量）
$num /= $float; // 将商除并分配给 $num
```
### 按位
:- | -
:- | -
`&` | 和
`|` | 或（包括或）
`^` | 异或（异或）
`~` | 不是
`<<` | 左移
`>>` | 右移
PHP 条件
------
### If elseif else
```php
$a = 10;
$b = 20;
if ($a > $b) {
echo "a is bigger than b";
} elseif ($a == $b) {
echo "a is equal to b";
} else {
echo "a is smaller than b";
}
```
### Switch
```php
$x = 0;
switch ($x) {
case '0':
print "it's zero";
break;
case 'two':
case 'three':
// do something
break;
default:
// do something
}
```
### 三元运算符
```php
# => Does
print (false ? 'Not' : 'Does');
$x = false;
# => Does
print($x ?: 'Does');
$a = null;
$b = 'Does print';
# => a is unsert
echo $a ?? 'a is unset';
# => print
echo $b ?? 'b is unset';
```
### 匹配
```php
$statusCode = 500;
$message = match($statusCode) {
200, 300 => null,
400 => '未找到',
500 => '服务器错误',
default => '已知状态码',
};
echo $message; # => 服务器错误
```
查看: [Match](https://www.php.net/manual/en/control-structures.match.php)
### 匹配表达式
```php
$age = 23;
$result = match (true) {
$age >= 65 => 'senior',
$age >= 25 => 'adult',
$age >= 18 => 'young adult',
default => 'kid',
};
echo $result; # => young adult
```
PHP 循环
------
### while 循环
```php
$i = 1;
# => 12345
while ($i <= 5) {
echo $i++;
}
```
### do while 循环
```php
$i = 1;
# => 12345
do {
echo $i++;
} while ($i <= 5);
```
### for i 循环
```php
# => 12345
for ($i = 1; $i <= 5; $i++) {
echo $i;
}
```
### break 跳出循环
```php
# => 123
for ($i = 1; $i <= 5; $i++) {
if ($i === 4) {
break;
}
echo $i;
}
```
### continue 继续
```php
# => 1235
for ($i = 1; $i <= 5; $i++) {
if ($i === 4) {
continue;
}
echo $i;
}
```
### foreach 循环
```php
$a = ['foo' => 1, 'bar' => 2];
# => 12
foreach ($a as $k) {
echo $k;
}
```
查看: [Array iteration](#关键迭代)
PHP 函数
------
### 返回值
```php
function square($x)
{
return $x * $x;
}
echo square(4); # => 16
```
### 返回类型
```php
// 基本返回类型声明
function sum($a, $b): float {/*...*/}
function get_item(): string {/*...*/}
class C {}
// 返回一个对象
function getC(): C { return new C; }
```
### 可空返回类型
```php
// 在 PHP 7.1 中可用
function nullOrString(int $v) : ?string
{
return $v % 2 ? "odd" : null;
}
echo nullOrString(3); # => odd
var_dump(nullOrString(4)); # => NULL
```
查看: [Nullable types](https://www.php.net/manual/en/migration71.new-features.php)
### 无效函数
```php
// 在 PHP 7.1 中可用
function voidFunction(): void
{
echo 'Hello';
return;
}
voidFunction(); # => Hello
```
### 变量函数
```php
function bar($arg = '')
{
echo "In bar(); arg: '$arg'.\n";
}
$func = 'bar';
$func('test'); # => In bar(); arg: test
```
### 匿名函数
```php
$greet = function($name)
{
printf("Hello %s\r\n", $name);
};
$greet('World'); # => Hello World
$greet('PHP'); # => Hello PHP
```
### 递归函数
```php
function recursion($x)
{
if ($x < 5) {
echo "$x";
recursion($x + 1);
}
}
recursion(1); # => 1234
```
### 默认参数
```php
function coffee($type = "cappuccino")
{
return "Making a cup of $type.\n";
}
# => 制作一杯卡布奇诺
echo coffee();
# => 制作一杯
echo coffee(null);
# => 制作一杯浓缩咖啡
echo coffee("espresso");
```
### 箭头函数
```php
$y = 1;
$fn1 = fn($x) => $x + $y;
// 相当于按值使用 $y：
$fn2 = function ($x) use ($y) {
return $x + $y;
};
echo $fn1(5); # => 6
echo $fn2(5); # => 6
```
PHP 类
------
### 构造函数 Constructor
```php
class Student {
public function __construct($name) {
$this->name = $name;
}
public function print() {
echo "Name: " . $this->name;
}
}
$alex = new Student("Alex");
$alex->print(); # => Name: Alex
```
### 继承 Inheritance
```php
class ExtendClass extends SimpleClass
{
// 重新定义父方法
function displayVar()
{
echo "Extending class\n";
parent::displayVar();
}
}
$extended = new ExtendClass();
$extended->displayVar();
```
### 类变量 Classes variables
<!--rehype:wrap-class=row-span-2-->
```php
class MyClass
{
const MY_CONST = 'value';
static $staticVar = 'static';
// 可见度
public static $var1 = 'pubs';
// 仅限类
private static $var2 = 'pris';
// 类和子类
protected static $var3 = 'pros';
// 类和子类
protected $var6 = 'pro';
// 仅限类
private $var7 = 'pri';
}
```
静态访问
```php
echo MyClass::MY_CONST; # => value
echo MyClass::$staticVar; # => static
```
### 魔术方法
```php
class MyClass
{
// 对象被视为字符串
public function __toString()
{
return $property;
}
// 与 __construct() 相反
public function __destruct()
{
print "Destroying";
}
}
```
### 接口
```php
interface Foo
{
public function doSomething();
}
interface Bar
{
public function doSomethingElse();
}
class Cls implements Foo, Bar
{
public function doSomething() {}
public function doSomethingElse() {}
}
```
各种各样的
------
### 基本错误处理
```php
try {
// 做一点事
} catch (Exception $e) {
// 处理异常
} finally {
echo "Always print!";
}
```
### PHP 8.0 中的异常
<!--rehype:wrap-class=col-span-2-->
```php {.wrap}
$nullableValue = null;
try {
$value = $nullableValue ?? throw new InvalidArgumentException();
} catch (InvalidArgumentException) { // 变量是可选的
// 处理我的异常
echo "print me!";
}
```
### 自定义异常
<!--rehype:wrap-class=row-span-2-->
```php
class MyException extends Exception {
// 做一点事
}
```
用法
```php
try {
$condition = true;
if ($condition) {
throw new MyException('bala');
}
} catch (MyException $e) {
// 处理我的异常
}
```
### Nullsafe 运算符
<!--rehype:wrap-class=row-span-2-->
```php
// 从 PHP 8.0.0 开始，这一行：
$result = $repo?->getUser(5)?->name;
// 相当于下面的代码：
if (is_null($repo)) {
$result = null;
} else {
$user = $repository->getUser(5);
if (is_null($user)) {
$result = null;
} else {
$result = $user->name;
}
}
```
另见: [Nullsafe 运算符](https://wiki.php.net/rfc/nullsafe_operator)
### 常用表达
```php
$str = "Visit Quickref.me";
echo preg_match("/qu/i", $str); # => 1
```
查看: [PHP中的正则表达式](./regex.md#php中的正则表达式)
### fopen() 模式
:- | -
:- | -
`r` | 读
`r+` | 读写，前置
`w` | 写入，截断
`w+` | 读写，截断
`a` | 写，追加
`a+` | 读写，追加
### 运行时定义的常量
```php
define("CURRENT_DATE", date('Y-m-d'));
// 一种可能的表示
echo CURRENT_DATE; # => 2021-01-05
# => CURRENT_DATE is: 2021-01-05
echo 'CURRENT_DATE is: ' . CURRENT_DATE;
```
另见
----
- [PHP 官方中文文档](https://www.php.net/manual/zh/index.php) _(php.net)_
- [Learn X in Y minutes](https://learnxinyminutes.com/docs/php/) _(learnxinyminutes.com)_