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 |
Previous: $_FILES, $_ENV, $_COOKIE, $_SESSION
Next: Integers and Floating point numbers
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.
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