Php 简明教程

PHP - Comparison Operators Examples

在 PHP 中，比较运算符用于比较两个值并确定它们之间的关系。这些运算符基于比较结果返回布尔值，即 True 或 False。

In PHP, Comparison operators are used to compare two values and determine their relationship. These operators return a Boolean value, either True or False, based on the result of the comparison.

下表突出显示了 PHP 支持的比较运算符。假定变量 $a 存储 10，变量 $b 存储 20，则−

The following table highligts the comparison operators that are supported by PHP. Assume variable $a holds 10 and variable $b holds 20, then −

Operator

Description

Example

==

Checks if the value of two operands are equal or not, if yes then condition becomes true.

($a == $b) is not true

!=

Checks if the value of two operands are equal or not, if values are not equal then condition becomes true.

($a != $b) is true

>

Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.

($a > $b) is false

<

Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.

($a < $b) is true

>=

Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.

($a >= $b) is false

⇐

Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.

($a ⇐ $b) is true

此外，这些运算符还可以与逻辑运算符（&&、||、！）结合使用，以在 PHP 程序的决策制定中形成复杂的条件。

Additionally, these operators can also be combined with logical operators (&&, ||, !) to form complex conditions for decision making in PHP programs.

Example

以下示例展示了如何在 PHP 中使用这些比较运算符：

The following example shows how you can use these comparison operators in PHP −

<?php
   $a = 42;
   $b = 20;

   if ($a == $b) {
      echo "TEST1 : a is equal to b \n";
   } else {
      echo "TEST1 : a is not equal to b \n";
   }

   if ($a > $b) {
      echo "TEST2 : a is greater than  b \n";
   } else {
      echo "TEST2 : a is not greater than b \n";
   }

   if ($a < $b) {
      echo "TEST3 : a is less than  b \n";
   } else {
      echo "TEST3 : a is not less than b \n";
   }

   if ($a != $b) {
      echo "TEST4 : a is not equal to b \n";
   } else {
      echo "TEST4 : a is equal to b \n";
   }

   if ($a >= $b) {
      echo "TEST5 : a is either greater than or equal to b \n";
   } else {
      echo "TEST5 : a is neither greater than nor equal to b \n";
   }
   if ($a <= $b) {
      echo "TEST6 : a is either less than or equal to b \n";
   } else {
      echo "TEST6 : a is neither less than nor equal to b";
   }
?>

它将生成以下 output −

It will produce the following output −

TEST1 : a is not equal to b
TEST2 : a is greater than b
TEST3 : a is not less than b
TEST4 : a is not equal to b
TEST5 : a is either greater than or equal to b
TEST6 : a is neither less than nor equal to b