PhP operator

PhP operator

In this section we will discuss the application of different operators in PHP.

In PHP, the assignment operator is used to assign values to variables.

In PHP, the arithmetic operator, plus, is used to add values together.

PHP arithmetic operator

The following example demonstrates the different results obtained using different arithmetic operators:

PHP assignment operator

In PHP, the basic assignment operator is "" I t means that the left operans are set to the value of the expression on the right. That is, $x value of "5" is 5.

The following example demonstrates the different results obtained using different assignment operators:

The following example demonstrates the same results with different string operators:

PHP increment/decrease operator

The following example demonstrates the results obtained using the increment/decrease operator:

PHP comparison operator

The comparison operator allows you to compare two values:

The following example demonstrates the different results obtained using some comparison operators:

PHP logical operator

PHP array operator

The following example demonstrates the different results obtained using some array operators:

PHP thyme operator

Another conditional operator is the ?: (or thymus) operator.

Grammar format:

(expr1) ? (expr2) : (expr3)

The value for expr1 is expr2 when true and expr3 when expr1 is false.

Starting with PHP 5.3, the middle part of the 3-function operator can be omitted. Expression expr1 ?: expr3 returns expr1 when expr1 is evaluated as TRUE, otherwise expr3 is returned.

Instance

In the following example, by judging that the $_GET request contains a user value, if there is a return of $_GET'user', otherwise nobody is returned:

Operator priority

Operators prioritize the grouping of terms in an expression. T his affects how expressions are evaluated. S ome operators take precedence over others;

The following table lists operators from highest to lowest by priority. Operators in the same row have the same priority, and their binding direction determines the order of the calculations.

In operator precedence, or and ||, and and are logical operators that have the same effect, but have different priorities.

<?php
// 优先级： &&  >  =  >  and
// 优先级： ||  >  =  >  or
 
$a = 3;
$b = false;
$c = $a or $b;
var_dump($c);          // 这里的 $c 为 int 值3，而不是 boolean 值 true
$d = $a || $b;
var_dump($d);          //这里的 $d 就是 boolean 值 true 
?>

The output of the above examples is:

int(3)
bool(true)

The use of parentheses

We use the pairing of parentheses to clearly indicate the order of operations, rather than relying on operator precedence and binding, which usually increases the readability of the code.

<?php
// 括号优先运算
 
$a = 1;
$b = 2;
$c = 3;
$d = $a + $b * $c;
echo $d;
echo "\n";
$e = ($a + $b) * $c;  // 使用括号
echo $e;
echo "\n";
?>

The output of the above examples is:

7
9