Php 简明教程

PHP - Operators Types

What are Operators in PHP?

与任何编程语言一样，PHP 也有运算符，它们是符号（有时 keywords ），被预先定义来对一个或多个操作数执行某些通常需要的操作。

As in any programming language, PHP also has operators which are symbols (sometimes keywords) that are predefined to perform certain commonly required operations on one or more operands.

例如，使用表达式“4 + 5”等于 9。此处“4”和“5”称为 operands ，而“+”称为 operator 。

For example, using the expression "4 + 5" is equal to 9. Here "4" and "5" are called operands and "+" is called an operator.

我们在 PHP 中具有以下类型的运算符 −

We have the following types of operators in PHP −

Arithmetic Operators
Comparison Operators
Logical Operators
Assignment Operators
String Operators
Array Operators
Conditional (or Ternary Operators)

本章将概述如何在 PHP 中使用这些运算符。在后续章节中，我们将仔细了解每个运算符及其工作原理。

This chapter will provide an overview of how you can use these operators in PHP. In the subsequent chapters, we will take a closer look at each of the operators and how they work.

Arithmetic Operators in PHP

我们使用算术运算符对给定的操作数执行加法、减法、乘法、除法等数学运算。算术运算符（不包括增量和减量运算符）始终对两个操作数起作用，但是这些操作数的类型应该相同。

We use Arithmetic operators to perform mathematical operations like addition, subtraction, multiplication, division, etc. on the given operands. Arithmetic operators (excluding the increment and decrement operators) always work on two operands, however the type of these operands should be the same.

下表高亮显示了 PHP 支持的算术运算符。假设变量“$a”保存了 42，而变量“$b”保存了 20 −

The following table highligts the arithmetic operators that are supported by PHP. Assume variable "$a" holds 42 and variable "$b" holds 20 −

Operator

Description

Example

Adds two operands

$a + $b = 62

Subtracts second operand from the first

$a - $b = 22

Multiply both operands

$a * $b = 840

Divide numerator by de-numerator

$a / $b = 2.1

Modulus Operator and remainder of after an integer division

$a % $b = 2

Increment operator, increases integer value by one

$a ++ = 43

—

Decrement operator, decreases integer value by one

$a — = 42

Comparison Operators in PHP

您将使用比较运算符来比较两个操作数并找出它们之间的关系。根据比较结果，它们返回一个布尔值（真或假）。

You would use Comparison operators to compare two operands and find the relationship between them. They return a Boolean value (either true or false) based on the outcome 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

Logical Operators in PHP

您可以在 PHP 中使用逻辑运算符对多个表达式一起执行逻辑运算。逻辑运算符始终返回布尔值，无论是真还是假。

You can use Logical operators in PHP to perform logical operations on multiple expressions together. Logical operators always return Boolean values, either true or false.

逻辑运算符通常与条件语句和循环一起使用，以根据布尔条件返回决策。在处理复杂表达式时，您还可以将它们组合起来，以操作布尔值。

Logical operators are commonly used with conditional statements and loops to return decisions according to the Boolean conditions. You can also combine them to manipulate Boolean values while dealing with complex expressions.

下表重点介绍了 PHP 支持的逻辑运算符。

The following table highligts the logical operators that are supported by PHP.

假设变量 $a 保存 10，变量 $b 保存 20，则 -

Assume variable $a holds 10 and variable $b holds 20, then −

Operator

Description

Example

and

Called Logical AND operator. If both the operands are true then condition becomes true.

(A and B) is true

Called Logical OR Operator. If any of the two operands are non zero then condition becomes true.

(A or B) is true

Called Logical AND operator. If both the operands are non zero then condition becomes true.

(A && B) is true

Called Logical OR Operator. If any of the two operands are non zero then condition becomes true.

B) is true

Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.

Assignment Operators in PHP

您可以在 PHP 中使用赋值运算符为给定变量分配或更新新值。赋值运算符的右侧保存值，而赋值运算符的左侧是将值分配到的变量。

You can use Assignment operators in PHP to assign or update the values of a given variable with a new value. The right-hand side of the assignment operator holds the value and the left-hand side of the assignment operator is the variable to which the value will be assigned.

双方的数据类型应该相同，否则您将收到一个错误。赋值运算符的结合性是从右向左。PHP 支持两种类型的赋值运算符 −

The data type of both the sides should be the same, else you will get an error. The associativity of assignment operators is from right to left. PHP supports two types of assignment operators −

Simple Assignment Operator − It is the most commonly used operator. It is used to assign value to a variable or constant.
Compound Assignment Operators − A combination of the assignment operator (=) with other operators like +, *, /, etc.

下表高亮显示了 PHP 支持的赋值运算符 −

The following table highligts the assignment operators that are supported by PHP −

Operator

Description

Example

Simple assignment operator, Assigns values from right side operands to left side operand

C = A + B will assign value of A + B into C

Add AND assignment operator, It adds right operand to the left operand and assign the result to left operand

C += A is equivalent to C = C + A

Subtract AND assignment operator, It subtracts right operand from the left operand and assign the result to left operand

C -= A is equivalent to C = C - A

Multiply AND assignment operator, It multiplies right operand with the left operand and assign the result to left operand

C *= A is equivalent to C = C * A

Divide AND assignment operator, It divides left operand with the right operand and assign the result to left operand

C /= A is equivalent to C = C / A

Modulus AND assignment operator, It takes modulus using two operands and assign the result to left operand

C %= A is equivalent to C = C % A

String Operators in PHP

PHP 中有两个运算符用于处理字符串数据类型 −

There are two operators in PHP for working with string data types −

The "." (dot) operator is PHP’s concatenation operator. It joins two string operands (characters of right hand string appended to left hand string) and returns a new string.
PHP also has the ".=" operator which can be termed as the concatenation assignment operator. It updates the string on its left by appending the characters of right hand operand.

$third = $first . $second;
$leftstring .= $rightstring;

Array Operators in PHP

PHP 定义了以下一组符号，用作数组数据类型的运算符−

PHP defines the following set of symbols to be used as operators on array data types −

Symbol

Example

Name

Result

$a + $b

Union

Union of $a and $b.

$a == $b

Equality

TRUE if $a and $b have the same key/value pairs.

===

$a === $b

Identity

TRUE if $a and $b have the same key/value pairs in the same order and of the same types.

$a != $b

Inequality

TRUE if $a is not equal to $b.

$a <> $b

Inequality

TRUE if $a is not equal to $b.

!==

$a !== $b

Non identity

TRUE if $a is not identical to $b.

Conditional Operators in PHP

PHP 中还有一个运算符称为条件运算符。它也被称为三元运算符。它首先为真或假值求值一个表达式，然后根据求值结果执行两个给定语句中的一个。

There is one more operator in PHP which is called conditional operator. It is also known as ternary operator. It first evaluates an expression for a true or false value and then executes one of the two given statements depending upon the result of the evaluation.

Operator

Description

Example

? :

Conditional Expression

If Condition is true ? Then value X : Otherwise value Y

Operator Categories in PHP

我们在上面讨论的所有运算符可以归类为以下几类−

All the operators we have discussed above can be categorised into following categories −

Unary prefix operators, which precede a single operand.
Binary operators, which take two operands and perform a variety of arithmetic and logical operations.
The conditional operator (a ternary operator), which takes three operands and evaluates either the second or third expression, depending on the evaluation of the first expression.
Assignment operators, which assign a value to a variable.

Operator Precedence in PHP

运算符的优先级决定了表达式中运算符执行的顺序。例如，在“2+6/3”中，6/3 的除法先执行，然后“2+2”的加法执行，因为除法运算符“/”的优先级高于加法运算符“+”。

Precedence of operators decides the order of execution of operators in an expression. For example, in "2+6/3", division of 6/3 is done first and then the addition of "2+2" takes place because the division operator "/" has higher precedence over the addition operator "+".

要强制在其他运算符之前调用某个运算符，应使用括号。在此示例中，(2+6)/3 首先执行加法，然后执行除法。

To force a certain operator to be called before other, parentheses should be used. In this example, (2+6)/3 performs addition first, followed by division.

某些运算符可能具有相同优先级。在这种情况下，关联顺序（左或右）决定运算顺序。具有相同优先级但非关联的运算符不能并列使用。

Some operators may have the same level of precedence. In that case, the order of associativity (either left or right) decides the order of operations. Operators of same precedence level but are non-associative cannot be used next to each other.

下表按运算符的优先级降序列出了 PHP 运算符 −

The following table lists the PHP operators in their decreasing order of precedence −

Operators

Purpose

clone new

clone and new

exponentiation

++ —

increment/decrement

~(int) (float) (string) (array) (object) (bool)

casting

instanceof

types

logical

* /

multiplication/division

modulo

+ - .

arithmetic and string

<< >>

bitwise shift

< ⇐ > >=

comparison

== != === !== <> <⇒

comparison

bitwise and/references

bitwise XOR

bitwise OR

logical and

logical or

null coalescing

? :

ternary

= += -= = *= /= .= %= &=

= ^= <⇐ >>= ??=

assignment operators

yield from

yield

and

logical

xor

logical