将字符串的True/False布尔值传递给函数参数 [英] Passing a String's True/False Boolean Value into a Functions Argument

问题描述

非常感谢您的阅读和回复.

Thank you so much for reading and responding if you can.

• 在一个函数中，我测试一个条件并创建一个字符串"true"或"false"，然后再创建一个全局变量.
• 然后我使用该字符串作为参数调用另一个函数

• 在该函数的if语句中，我要基于'true'或'false'的字符串布尔值进行测试

• In one function I test a condition and make a string 'true' or 'false', which then I make a global variable.
• Then I call another function with that string as the parameter

• Within that function's if statement, I want to test based off the strings boolean value of 'true' or 'false'

$email_form_comments = $_POST['comments']; // pull post data from form

if ($email_form_comments) $comments_status = true;  // test if $email_form_comments is instantiated. If so, $comments_status is set to true
else $error = true; // if not, error set to true. 

test_another_condition($comments_status); // pass $comments_status value as parameter 

function test_another_condition($condition) {

    if($condition != 'true') {    // I expect $condition to == 'true'parameter
      $output = "Your Condition Failed";
      return $output;
     }

}

我的想法是$ condition将具有"true"值，但事实并非如此.

My thinking is that $condition will hold a 'true' value, but this is not so.

推荐答案

我认为这里的关键是PHP会将空字符串评估为false，将非空字符串评估为true，并且在设置和比较布尔值时请确保使用常量而不引号.使用true或false而不是'true'或'false'.另外，建议您编写if语句，以便它们在单个变量上设置替代值，或者在条件失败时函数返回替代值的情况下.

I think the key here is PHP will evaluate empty strings as false and non-empty strings as true, and when setting and comparing booleans make sure to use constants without quotes. Use true or false not 'true' or 'false'. Also, I suggest writing your if statements so they will set alternate values on a single variable, or in the case of a function return an alternate value when the condition fails.

我对您的代码做了一些小的修改，以便您的函数可以评估为真

I made some small modifications to your code so that your function will evaluate true

// simulate post content
$_POST['comments'] = 'foo'; // non-empty string will evaluate true
#$_POST['comments'] = ''; // empty string will evaluate false

$email_form_comments = $_POST['comments']; // pull post data from form

if ($email_form_comments) {
  $comments_status = true;  // test if $email_form_comments is instantiated. If so, $comments_status is set to true
} else {
  $comments_status = false; // if not, error set to true. 
}

echo test_another_condition($comments_status); // pass $comments_status value as parameter 

function test_another_condition($condition)
{
    if ($condition !== true) { 
      return 'Your Condition Failed';
    }

    return 'Your Condition Passed';
}

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