Collection of php operators

Everyone will come into contact with operators when learning programming languages. This article mainly shares with you a collection of PHP operators, hoping to help everyone.

1. Operator precedence
Increment/Decrease> ! > Arithmetic operators> Size comparison> (Not)Equality comparison> Reference>
Bit operator (^ ) > bit operator (|) > logical AND > logical OR > ternary > assignment > and > Use

2. Comparison operators
2.1, the difference between == and ===
==: Comparison value
===: Comparison value and comparison type

2.2. Judgment of equality (seven cases of FALSE)
0, 0.0, ' ', '0', false, array(), null

2.3. Increasing and decrementing does not affect the Boolean value

2.4. Decreasing the NULL value has no effect, but increasing the NULL value is 1

3. Logical operators
3.1. Short-circuit effect
$a = true || $b == 3 ;//$b is not executed
$b = false && $a == 1;//$a is not executed

3.2, || and && have different priorities from or and and
&& > || > and > or

$a = false || true; //true
$b = false or true; // false



4. Example

<?php

/**
 * 下列程序中请写出打印输出的结果
 * <?php
 *
 * $a = 0;
 * $b = 0;
 *
 * if ($a = 3 > 0 || $b = 3 > 0) 
 * {
 *      $a++;
 *      $b++;
 *      echo $a. "\n";
 *      echo $b. "\n";
 * }
 */
$a = 0;
$b = 0;

if ($a = 3 > 0 || $b = 3 > 0) 
{
/**
*	> 的优先级大于 || 大于 =
*	因此可以认为是
*	$a = ((3 > 0) || $b = 3 > 0)
*	=> $a = (true || $b = 3 > 0)
*	由于逻辑或短路作用，b 不再执行
*	因此：$a = true， b = 0
*	由于布尔值递增和递减都不影响还是true，而打印echo时，true底层转为1
*	因此最终echo a 和 b，都是1
*/
    $a++;
    $b++;
    echo $a. "\n";
    echo $b. "\n";
}

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