PHP Data Types: Booleans
Description
Booleans are the easiest type. It can be either TRUE or FALSE. It is used in control structure like the testing portion of an if statement.
Consider the following example :
<?php
$height=100;
$width=50;
if ($width == 0)
{
echo "The width needs to be a non-zero number";
}
?>
In the above code the result of the equal-than operator is a Boolean. In this case, it would be false and, therefore, the echo statement will never execute.
Now consider the next example:
<?php
$height=100;
$width=50;
if ($width)
{
echo "The area of the rectangle is".$height*$width;
}
else
{
echo "The width needs to be a non-zero number";
}
?>
In this example no comparison operator is used. But PHP automatically converted $width value 50 to its Boolean equivalent true and calculate the area of the rectangle i.e. execute the commands inside the if() statement.
List of the types of Boolean values equivalents
Data Type | True Value | False value |
---|---|---|
Integer | All non-zero values | 0 |
Floating point | All non-zero values | 0.0 |
Strings | All other strings | Empty strings ()"" The zero string ()"0" |
Null | Never | Always |
Array | If it contains at least one element |
If it does not contain any elements |
Object | Always | Never |
Resource | Always | Never |
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Next: Integers and Floating point numbers
PHP: Tips of the Day
How to Sort Multi-dimensional Array by Value?
Try a usort, If you are still on PHP 5.2 or earlier, you'll have to define a sorting function first:
Example:
function sortByOrder($a, $b) { return $a['order'] - $b['order']; } usort($myArray, 'sortByOrder');
Starting in PHP 5.3, you can use an anonymous function:
usort($myArray, function($a, $b) { return $a['order'] - $b['order']; });
And finally with PHP 7 you can use the spaceship operator:
usort($myArray, function($a, $b) { return $a['order'] <=> $b['order']; });
To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero - best explained below. You can also use this for sorting on sub-elements.
usort($myArray, function($a, $b) { $retval = $a['order'] <=> $b['order']; if ($retval == 0) { $retval = $a['suborder'] <=> $b['suborder']; if ($retval == 0) { $retval = $a['details']['subsuborder'] <=> $b['details']['subsuborder']; } } return $retval; });
If you need to retain key associations, use uasort() - see comparison of array sorting functions in the manual
Ref : https://bit.ly/3i77vCC
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