如何将字符串转换为布尔值 php

问题描述

如何将字符串转换为boolean?

$string = 'false';

$test_mode_mail = settype($string, 'boolean');

var_dump($test_mode_mail);

if($test_mode_mail) echo 'test mode is on.';

它返回，

布尔真

但它应该是boolean false.

推荐答案

除非字符串的值被 PHP 视为空"(取自 empty 文档):

Strings always evaluate to boolean true unless they have a value that's considered "empty" by PHP (taken from the documentation for empty):

1. "" (一个空字符串);
2. "0" (0 作为字符串)

1. "" (an empty string);
2. "0" (0 as a string)

如果您需要根据字符串的文本值设置布尔值，则需要检查该值是否存在.

If you need to set a boolean based on the text value of a string, then you'll need to check for the presence or otherwise of that value.

$test_mode_mail = $string === 'true'? true: false;

上面的代码是为了清楚地理解.在实际使用中，下面的代码可能更合适:

the above code is intended for clarity of understanding. In actual use the following code may be more appropriate:

$test_mode_mail = ($string === 'true');

或者使用 filter_var 函数可能会覆盖更多的布尔值:

or maybe use of the filter_var function may cover more boolean values:

filter_var($string, FILTER_VALIDATE_BOOLEAN);

filter_var 涵盖整个范围的值，包括真值 "true", "1", "yes" 和 on".请参阅此处了解更多详情.

filter_var covers a whole range of values, including the truthy values "true", "1", "yes" and "on". See here for more details.

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