php备忘录源码 PHP 备忘录

<?php // begin with a PHP open tag.

echo "Hello Worldn";
print("Hello quickref.me");

?>

PHP运行命令

$ php hello.php

$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

$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

$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

$x = 1;
$y = 2;

$sum = $x + $y;
echo $sum;   # => 3

请参阅：运算符

运算符

$x = 1;
$y = 2;

$sum = $x + $y;
echo $sum;   # => 3

function add($num1, $num2 = 1) {
    return $num1 + $num2;
}
echo add(10);    # => 11
echo add(10, 5); # => 15

请参阅：函数

# This is a one line shell-style comment

// This is a one line c++ style comment

const MY_CONST = "hello";

echo MY_CONST;   # => hello

# => MY_CONST is: hello
echo "MY_CONST is: " . MY_CONST; 

class Student {
    public function __construct($name) {
        $this->name = $name;
    }
}
$alex = new Student("Alex");

请参阅：类

echo "this is a simple string";

请参阅：字符串

$arr = array("hello", "world", "!");

请参阅：数组

$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

$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

function bar(): iterable {
    return [1, 2, 3];
}
function gen(): iterable {
    yield 1;
    yield 2;
    yield 3;
}
foreach (bar() as $value) {
    echo $value;   # => 123
} 

# => "$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";

$str = "foo";

// Uninterpolated multi-liners
$nowdoc = <<<"END"
Multi line string
$str
END;

// Will do string interpolation
$heredoc = <<<END
Multi line
$str
END;

$s = "Hello Phper";
echo strlen($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

$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

$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

$array = array("a", "b", "c");
$count = count($array);

for ($i = 0; $i < $count; $i++) {
    echo "i:{$i}, v:{$array[$i]}n";
}

$colors = array("red", "blue", "green");

foreach ($colors as $color) {
    echo "Do you like $color?n";
}

$arr = ["foo" => "bar", "bar" => "foo"];

foreach ( $arr as $key => $value )
{
  	echo "key: " . $key . "n";
    echo "val: {$arr[$key]}n";
}

$a = [1, 2];
$b = [3, 4];

// PHP 7.4 later
# => [1, 2, 3, 4]
$result = [...$a, ...$b];

$array = [1, 2];

function foo(int $a, int $b) {
	echo $a; # => 1
  	echo $b; # => 2
}
foo(...$array);

function foo($first, ...$other) {
	var_dump($first); # => a
  	var_dump($other); # => ["b", "c"]
}
foo("a", "b", "c"  );
// or
function foo($first, string ...$other){}

$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";
}

$x = 0;
switch ($x) {
    case "0":
        print "it"s zero";
        break; 
    case "two":
    case "three":
        // do something
        break;
    default:
        // do something
}

# => 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";

$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

$age = 23;

$result = match (true) {
    $age >= 65 => "senior",
    $age >= 25 => "adult",
    $age >= 18 => "young adult",
    default => "kid",
};

echo $result; # => young adult

$i = 1;
# => 12345
while ($i <= 5) {
    echo $i++;
}

$i = 1;
# => 12345
do {
    echo $i++;
} while ($i <= 5);

# => 12345
for ($i = 1; $i <= 5; $i++) {
    echo $i;
}

# => 123
for ($i = 1; $i <= 5; $i++) {
    if ($i === 4) {
        break;
    }
    echo $i;
}

# => 1235
for ($i = 1; $i <= 5; $i++) {
    if ($i === 4) {
        continue;
    }
    echo $i;
}

$a = ["foo" => 1, "bar" => 2];
# => 12
foreach ($a as $k) {
    echo $k;
}

请参阅：数组迭代

function square($x)
{
    return $x * $x;
}

echo square(4);  # => 16

// Basic return type declaration
function sum($a, $b): float {}
function get_item(): string {}

class C {}
// Returning an object
function getC(): C { return new C; }

// 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

// Available in PHP 7.1
function voidFunction(): void
{
	echo "Hello";
	return;
}

voidFunction();  # => Hello

function bar($arg = "")
{
    echo "In bar(); arg: "$arg".n";
}

$func = "bar";
$func("test"); # => In bar(); arg: test

$greet = function($name)
{
    printf("Hello %srn", $name);
};

$greet("World"); # => Hello World
$greet("PHP");   # => Hello PHP

function recursion($x)
{
    if ($x < 5) {
        echo "$x";
        recursion($x + 1);
    }
}
recursion(1);  # => 1234

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");

$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

class Student {
    public function __construct($name) {
        $this->name = $name;
    }
  	public function print() {
        echo "Name: " . $this->name;
    }
}
$alex = new Student("Alex");
$alex->print();    # => Name: Alex

class ExtendClass extends SimpleClass
{
    // Redefine the parent method
    function displayVar()
    {
        echo "Extending classn";
        parent::displayVar();
    }
}

$extended = new ExtendClass();
$extended->displayVar();

class MyClass
{
    // Object is treated as a String
    public function __toString()
    {
        return $property;
    }
    // opposite to __construct()
    public function __destruct()
    {
        print "Destroying";
    }
}

interface Foo 
{
    public function doSomething();
}
interface Bar
{
    public function doSomethingElse();
}
class Cls implements Foo, Bar 
{
    public function doSomething() {}
    public function doSomethingElse() {}
}

try {
    // Do something
} catch (Exception $e) {
    // Handle exception
} finally {
    echo "Always print!";
}

$str = "Visit Quickref.me";
echo preg_match("/qu/i", $str); # => 1

请参阅：PHP 中的正则表达式

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;