此PHP备忘单提供了一个参考，可用于快速查找您最常使用的代码的正确语法。
开始
hello.php
PHP运行命令
$ php hello.php
变量
$boolean1 = true;
$boolean2 = True;
$int = 12;
$float = 3.1415926;
unset($float); // Delete variable
$str1 = "How are you?";
$str2 = 'Fine, thanks';
请参阅：类型
字符串
$url = "quickref.me";
echo "I'm learning PHP at $url";
// Concatenate strings
echo "I'm learning PHP at " . $url;
$hello = "Hello, ";
$hello .= "World!";
echo $hello; # => Hello, World!
请参阅：字符串
数组
$num = [1, 3, 5, 7, 9];
$num[5] = 11;
unset($num[2]); // Delete variable
print_r($num); # => 1 3 7 9 11
echo count($num); # => 5
请参阅：数组
运算符
Include
变量文件
测试文件
apple
/* Same as include,
cause an error if cannot be included*/
require 'vars.php';
// Also works
include('vars.php');
require('vars.php');
// Include through HTTP
include 'http://x.com/file.php';
// Include and the return statement
$result = include 'vars.php';
echo $result; # => Anything you like.
?>
函数
function add($num1, $num2 = 1) {
return $num1 + $num2;
}
echo add(10); # => 11
echo add(10, 5); # => 15
请参阅：函数
注释
# This is a one line shell-style comment
// This is a one line c++ style comment
/* This is a multi line comment
yet another line of comment */
常数
const MY_CONST = "hello";
echo MY_CONST; # => hello
# => MY_CONST is: hello
echo 'MY_CONST is: ' . MY_CONST;
类
class Student {
public function __construct($name) {
$this->name = $name;
}
}
$alex = new Student("Alex");
请参阅：类
PHP 类型
布尔值
$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
$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：整数
字符串
echo 'this is a simple string';
请参阅：字符串
数组
$arr = array("hello", "world", "!");
请参阅：数组
浮动（double）
$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
空值
$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
function bar(): iterable {
return [1, 2, 3];
}
function gen(): iterable {
yield 1;
yield 2;
yield 3;
}
foreach (bar() as $value) {
echo $value; # => 123
}
PHP 字符串
String
# => '$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';
Multi line
$str = "foo";
// Uninterpolated multi-liners
$nowdoc = <<<'END'
Multi line string
$str
END;
// Will do string interpolation
$heredoc = <<操作
$s = "Hello Phper";
echo strlen($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
请参阅：字符串函数
PHP 数组
定义
$a1 = ["hello", "world", "!"]
$a2 = array("hello", "world", "!");
$a3 = explode(",", "apple,pear,peach");
混合 int 和 string 键
$array = array(
"foo" => "bar",
"bar" => "foo",
100 => -100,
-100 => 100,
);
var_dump($array);
短数组语法
$array = [
"foo" => "bar",
"bar" => "foo",
];
多维度
$multiArray = [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9],
];
print_r($multiArray[0][0]) # => 1
print_r($multiArray[0][1]) # => 2
print_r($multiArray[0][2]) # => 3
多类型
$array = array(
"foo" => "bar",
42 => 24,
"multi" => array(
"dim" => array(
"a" => "foo"
)
)
);
# => string(3) "bar"
var_dump($array["foo"]);
# => int(24)
var_dump($array[42]);
# => string(3) "foo"
var_dump($array["multi"]["dim"]["a"]);
操作
$arr = array(5 => 1, 12 => 2);
$arr[] = 56; // Append
$arr["x"] = 42; // Add with key
sort($arr); // Sort
unset($arr[5]); // Remove
unset($arr); // Remove all
请参阅：数组函数
索引迭代
$array = array('a', 'b', 'c');
$count = count($array);
for ($i = 0; $i < $count; $i++) {
echo "i:{$i}, v:{$array[$i]}\n";
}
值迭代
$colors = array('red', 'blue', 'green');
foreach ($colors as $color) {
echo "Do you like $color?\n";
}
关键迭代
$arr = ["foo" => "bar", "bar" => "foo"];
foreach ( $arr as $key => $value )
{
echo "key: " . $key . "\n";
echo "val: {$arr[$key]}\n";
}
串联数组
$a = [1, 2];
$b = [3, 4];
// PHP 7.4 later
# => [1, 2, 3, 4]
$result = [...$a, ...$b];
函数调用
$array = [1, 2];
function foo(int $a, int $b) {
echo $a; # => 1
echo $b; # => 2
}
foo(...$array);
Splat 操作符
function foo($first, ...$other) {
var_dump($first); # => a
var_dump($other); # => ['b', 'c']
}
foo('a', 'b', 'c' /*, ...*/ );
// or
function foo($first, string ...$other){}
PHP 运算符
算术
+ |
添加 |
- |
减法 |
* |
乘法 |
/ |
分配 |
% |
模数 |
** |
求幂 |
赋值
a += b |
与...一样 a = a + b |
a -= b |
与...一样 a = a – b |
a *= b |
与...一样 a = a * b |
a /= b |
与...一样 a = a / b |
a %= b |
与...一样 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
and |
和 |
or |
或者 |
xor |
独占或 |
! |
不是 |
&& |
和 |
|| |
或者 |
算术
// Arithmetic
$sum = 1 + 1; // 2
$difference = 2 - 1; // 1
$product = 2 * 2; // 4
$quotient = 2 / 1; // 2
// Shorthand arithmetic
$num = 0;
$num += 1; // Increment $num by 1
echo $num++; // Prints 1 (increments after evaluation)
echo ++$num; // Prints 3 (increments before evaluation)
$num /= $float; // Divide and assign the quotient to $num
位
& |
和 |
| |
或（包括或） |
^ |
Xor（异或） |
~ |
不是 |
<< |
左移 |
>> |
右移 |
PHP 条件
if else
$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
$x = 0;
switch ($x) {
case '0':
print "it's zero";
break;
case 'two':
case 'three':
// do something
break;
default:
// do something
}
三元运算符
# => 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
$statusCode = 500;
$message = match($statusCode) {
200, 300 => null,
400 => 'not found',
500 => 'server error',
default => 'known status code',
};
echo $message; # => server error
参见：匹配
匹配表达式
$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
$i = 1;
# => 12345
while ($i <= 5) {
echo $i++;
}
Do while
$i = 1;
# => 12345
do {
echo $i++;
} while ($i <= 5);
for i
# => 12345
for ($i = 1; $i <= 5; $i++) {
echo $i;
}
break
# => 123
for ($i = 1; $i <= 5; $i++) {
if ($i === 4) {
break;
}
echo $i;
}
continue
# => 1235
for ($i = 1; $i <= 5; $i++) {
if ($i === 4) {
continue;
}
echo $i;
}
foreach
$a = ['foo' => 1, 'bar' => 2];
# => 12
foreach ($a as $k) {
echo $k;
}
请参阅：数组迭代
PHP 函数
返回值
function square($x)
{
return $x * $x;
}
echo square(4); # => 16
返回类型
// Basic return type declaration
function sum($a, $b): float {/*...*/}
function get_item(): string {/*...*/}
class C {}
// Returning an object
function getC(): C { return new C; }
可空返回类型
// Available in PHP 7.1
function nullOrString(int $v) : ?string
{
return $v % 2 ? "odd" : null;
}
echo nullOrString(3); # => odd
var_dump(nullOrString(4)); # => NULL
请参阅：可空类型
空函数
// Available in PHP 7.1
function voidFunction(): void
{
echo 'Hello';
return;
}
voidFunction(); # => Hello
变量函数
function bar($arg = '')
{
echo "In bar(); arg: '$arg'.\n";
}
$func = 'bar';
$func('test'); # => In bar(); arg: test
匿名函数
$greet = function($name)
{
printf("Hello %s\r\n", $name);
};
$greet('World'); # => Hello World
$greet('PHP'); # => Hello PHP
递归函数
function recursion($x)
{
if ($x < 5) {
echo "$x";
recursion($x + 1);
}
}
recursion(1); # => 1234
默认参数
function coffee($type = "cappuccino")
{
return "Making a cup of $type.\n";
}
# => Making a cup of cappuccino.
echo coffee();
# => Making a cup of .
echo coffee(null);
# => Making a cup of espresso.
echo coffee("espresso");
箭头函数
$y = 1;
$fn1 = fn($x) => $x + $y;
// equivalent to using $y by value:
$fn2 = function ($x) use ($y) {
return $x + $y;
};
echo $fn1(5); # => 6
echo $fn2(5); # => 6
PHP 类
构造函数
class Student {
public function __construct($name) {
$this->name = $name;
}
public function print() {
echo "Name: " . $this->name;
}
}
$alex = new Student("Alex");
$alex->print(); # => Name: Alex
继承
class ExtendClass extends SimpleClass
{
// Redefine the parent method
function displayVar()
{
echo "Extending class\n";
parent::displayVar();
}
}
$extended = new ExtendClass();
$extended->displayVar();
类变量
class MyClass
{
const MY_CONST = 'value';
static $staticVar = 'static';
// Visibility
public static $var1 = 'pubs';
// Class only
private static $var2 = 'pris';
// The class and subclasses
protected static $var3 = 'pros';
// The class and subclasses
protected $var6 = 'pro';
// The class only
private $var7 = 'pri';
}
静态访问
echo MyClass::MY_CONST; # => value
echo MyClass::$staticVar; # => static
魔术方法
class MyClass
{
// Object is treated as a String
public function __toString()
{
return $property;
}
// opposite to __construct()
public function __destruct()
{
print "Destroying";
}
}
接口
interface Foo
{
public function doSomething();
}
interface Bar
{
public function doSomethingElse();
}
class Cls implements Foo, Bar
{
public function doSomething() {}
public function doSomethingElse() {}
}
其他
基本错误处理
try {
// Do something
} catch (Exception $e) {
// Handle exception
} finally {
echo "Always print!";
}
PHP 8.0 中的异常
$nullableValue = null;
try {
$value = $nullableValue ?? throw new InvalidArgumentException();
} catch (InvalidArgumentException) { // Variable is optional
// Handle my exception
echo "print me!";
}
自定义异常
class MyException extends Exception {
// do something
}
用法
try {
$condition = true;
if ($condition) {
throw new MyException('bala');
}
} catch (MyException $e) {
// Handle my exception
}
空安全运算符
// As of PHP 8.0.0, this line:
$result = $repo?->getUser(5)?->name;
// Equivalent to the following code:
if (is_null($repo)) {
$result = null;
} else {
$user = $repository->getUser(5);
if (is_null($user)) {
$result = null;
} else {
$result = $user->name;
}
}
另见：空安全运算符
常用表达
$str = "Visit Quickref.me";
echo preg_match("/qu/i", $str); # => 1
请参阅：PHP 中的正则表达式
fopen() 模式
r |
读 |
r+ |
读取和写入，前置 |
w |
写，截断 |
w+ |
读写，截断 |
a |
写入，追加 |
a+ |
读写，追加 |
运行时定义的常量
define("CURRENT_DATE", date('Y-m-d'));
// One possible representation
echo CURRENT_DATE; # => 2021-01-05
# => CURRENT_DATE is: 2021-01-05
echo 'CURRENT_DATE is: ' . CURRENT_DATE;
另见
- PHP 文档
- 在 Y 分钟内学习 X