逻辑运算符php true或false [英] Logical operators php true or false

问题描述

作为php neewbie，我尝试阅读很多其他人的代码以进行学习. 今天我遇到了这样的一行:

As a php neewbie , I try to read a lot of other people´s code in order to learn. Today I came across a line like this :

if ( stripos($post_to_check->post_content, '[' . $shortcode) !== false )

我想知道两者之间有什么区别 !==false和==true 如果有人可以向我解释这一点，将不胜感激. ..如果没有真正的区别-使用引号中的一个而不是另一个使用引号的原因是什么?

I was wondering what is the difference between !==false and ==true If someone can explain that to me, It would be greatly appreciated. ..and if there is no real difference - what would be the reasons to use the quoted one over the other ??

推荐答案

PHP是一种松散类型的语言. ==匹配两个值，===匹配值以及值的数据类型.

PHP is a loosely typed language. == match the both values and === match the values as well as the data type of values.

if (8 == '8') // returns true

以上条件仅匹配值而不是数据类型，因此if评估为TRUE

Above condition just match the values not the data type hence if evaluate to TRUE

if (8 === '8') // returns false

并且此值同时检查值和值的数据类型，因此此if评估为FALSE

and this one check both value and data type of values hence this if evaluate to FALSE

您使用===来同时检查值和数据类型，并在需要仅比较值而不是数据类型时使用==.

you use === where you want to check the value and data type both and use == when you need to compare only values not the data type.

就您而言，

stripos返回子字符串在字符串中的位置，如果找不到字符串，则返回FALSE.

The stripos returns the position of the sub string in the string, if string not found it returns FALSE.

if ( stripos($post_to_check->post_content, '[' . $shortcode) !== false )

上面的代码检查字符串内的子字符串，并仅在找到子字符串时对TRUE求值. 如果将其更改为

The code above check sub string inside string and get evaluate to TRUE only when the sub string found. If you change it to

if ( stripos($post_to_check->post_content, '[' . $shortcode) != false )

，并且在0位置找到子字符串时，即使主字符串中存在子字符串，if也会评估为FALSE. 这样情况就会变成这样

and when the sub string found at the 0 position the if evaluate to FALSE even when sub string is there in the main string. Then the condition will become like this

if ( 0 != false )

，由于0被认为是FALSE

所以您必须在这里使用!==

So you have to use there !==

if ( 0 !== false )

这将比较两个值的值和数据类型 值0是整数类型，而false是boolean类型，因此此处的数据类型不匹配，条件将为TRUE

This will compare the values and data type of both values The value 0 is an integer type and the false is boolean type, hence the data type does not match here and condition will be TRUE

PHP手册页指出了这些比较运算符，您应该检查一次.

PHP manual page states these comparison operator you should check this once.

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