什么是 PHP 中的运算符

运算符是告诉 PHP 处理器执行某些操作的符号。例如， 加法符号是告诉 PHP 添加两个变量或值的运算符，而大于 符号是告诉 PHP 比较两个值的运算符。+`>`

以下列表描述了 PHP 中使用的不同运算符。

PHP 算术运算符

算术运算符用于执行常见的算术运算，例如加法、减法、乘法等。以下是 PHP 的算术运算符的完整列表：

以下示例将向您展示这些算术运算符的实际应用：

<?php
$x = 10;
$y = 4;
echo($x + $y); // 0utputs: 14
echo($x - $y); // 0utputs: 6
echo($x * $y); // 0utputs: 40
echo($x / $y); // 0utputs: 2.5
echo($x % $y); // 0utputs: 2
?>

PHP 赋值运算符

赋值运算符用于为变量赋值。

以下示例将向您展示这些赋值运算符的实际应用：

<?php
$x = 10;
echo $x; // Outputs: 10
$x = 20;
$x += 30;
echo $x; // Outputs: 50
$x = 50;
$x -= 20;
echo $x; // Outputs: 30
$x = 5;
$x *= 25;
echo $x; // Outputs: 125
$x = 50;
$x /= 10;
echo $x; // Outputs: 5
$x = 100;
$x %= 15;
echo $x; // Outputs: 10
?>

PHP 比较运算符

比较运算符用于以布尔方式比较两个值。

以下示例将向您展示这些比较运算符的实际应用：

<?php
$x = 25;
$y = 35;
$z = "25";
var_dump($x == $z);  // Outputs: boolean true
var_dump($x === $z); // Outputs: boolean false
var_dump($x != $y);  // Outputs: boolean true
var_dump($x !== $z); // Outputs: boolean true
var_dump($x < $y);   // Outputs: boolean true
var_dump($x > $y);   // Outputs: boolean false
var_dump($x <= $y);  // Outputs: boolean true
var_dump($x >= $y);  // Outputs: boolean false
?>

PHP 递增和递减运算符

递增/递减运算符用于递增/递减变量的值。

以下示例将向您展示这些递增和递减运算符的实际应用：

<?php
$x = 10;
echo ++$x; // Outputs: 11
echo $x;   // Outputs: 11
$x = 10;
echo $x++; // Outputs: 10
echo $x;   // Outputs: 11
$x = 10;
echo --$x; // Outputs: 9
echo $x;   // Outputs: 9
$x = 10;
echo $x--; // Outputs: 10
echo $x;   // Outputs: 9
?>

PHP 逻辑运算符

The logical operators are typically used to combine conditional statements.

The following example will show you these logical operators in action:

<?php
$year = 2014;
// Leap years are divisible by 400 or by 4 but not 100
if(($year % 400 == 0) || (($year % 100 != 0) && ($year % 4 == 0))){
    echo "$year is a leap year.";
} else{
    echo "$year is not a leap year.";
}
?>

PHP 字符串运算符

有两个专门为字符串设计的运算符。

以下示例将向您展示这些字符串运算符的实际应用：

<?php
$x = "Hello";
$y = " World!";
echo $x . $y; // Outputs: Hello World!
$x .= $y;
echo $x; // Outputs: Hello World!
?>

PHP 数组运算符

The array operators are used to compare arrays:

The following example will show you these array operators in action:

<?php
$x = array("a" => "Red", "b" => "Green", "c" => "Blue");
$y = array("u" => "Yellow", "v" => "Orange", "w" => "Pink");
$z = $x + $y; // Union of $x and $y
var_dump($z);
var_dump($x == $y);   // Outputs: boolean false
var_dump($x === $y);  // Outputs: boolean false
var_dump($x != $y);   // Outputs: boolean true
var_dump($x <> $y);   // Outputs: boolean true
var_dump($x !== $y);  // Outputs: boolean true
?>

PHP Spaceship Operator PHP 7

PHP 7 introduces a new spaceship operator (<=>) which can be used for comparing two expressions. It is also known as combined comparison operator.

The spaceship operator returns 0 if both operands are equal, 1 if the left is greater, and -1 if the right is greater. It basically provides three-way comparison as shown in the following table:

The following example will show you how spaceship operator actually works:

<?php
// Comparing Integers 
echo 1 <=> 1; // Outputs: 0
echo 1 <=> 2; // Outputs: -1
echo 2 <=> 1; // Outputs: 1

// Comparing Floats
echo 1.5 <=> 1.5; // Outputs: 0
echo 1.5 <=> 2.5; // Outputs: -1
echo 2.5 <=> 1.5; // Outputs: 1

// Comparing Strings
echo "x" <=> "x"; // Outputs: 0
echo "x" <=> "y"; // Outputs: -1
echo "y" <=> "x"; // Outputs: 1
?>