w3resource

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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PHP: Tips of the Day

In PHP, there are two versions of logical AND and OR operators.

Operator True if
$a and $b Both $a and $b are true
$a && $b Both $a and $b are true
$a or $b Either $a or $b is true
$a || $b Either $a or $b is true

Note that the && and || opererators have higher precedence than and and or. See table below:

Evaluation Result of $e Evaluated as
$e = false || true True $e = (false || true)
$e = false or true False ($e = false) or true

Because of this it's safer to use && and || instead of and and or.