Is an array considered as boolean true in php?

问题

I have a quick question here. I know that the cakePHP find('first') function returns an array containing the first result if found, false otherwise. My question is this, what if I were to write a check like this:

if(result_is_array) // that means I have data
{
    // do something
}
else // that means result is a boolean
{
    // do something else
}

Instead of checking whether the result obtained from find('first') is an array or not, can I just say:

$result = $this->MyModel->find('first');
if($result)
{
    // do something
}

In order words, if I get an array here, will that evaluate to TRUE in php? Is if(array()) equal to true in php?

回答1:

YES you can do

$result = $this->MyModel->find('first');
if($result)

An array with length > 0 returns true

Explanation is here in the docs

When converting to boolean, the following values are considered FALSE

an array with zero elements

Every other value is considered TRUE

回答2:

Instead of checking whether the result obtained from find('first') is an array or not

Yes. Do it the second way:if ($result). If find returns an empty array or boolean false, the branch will not be executed.

The best part about doing it this way is that it makes it clear to the reader that you are checking for a non-empty value.

回答3:

A zero value array is false

An array with values in it is true

You can view this table to see what is evaluated as true vs false.

回答4:

According to the documentation, if you try to treat an array as a boolean, the array will be considered true precisely when it's not empty.

回答5:

Use the following if you are looking for a TRUE value:

if ( $result !== false )
{
    // do something
}

回答6:

An empty array will always evaluate to false or if it contain any key/values then it will evaluate to true. if $this->MyModel->find('first'); always returns an array then an empty result will evaluate to false and true other wise. so your code is perfectly valid.

来源：https://stackoverflow.com/questions/9843077/is-an-array-considered-as-boolean-true-in-php

标签

php

casting

type-conversion