PHP Boolean type

This is the simplest type. Boolean expresses the truth value, which can be TRUE or FALSE.

Note: The Boolean type is introduced in PHP 4.

Grammar

To specify a Boolean value, use the keyword TRUE or FALSE. Two are not case-sensitive.

<?php
$foo = True; // assign the value TRUE to $foo
?>

Typically you return a boolean value with some operators and pass it to the control flow.

<?php
// ==  is an operator that detects whether two variables are equal and returns a Boolean value of
if  ( $action   ==  "Show_version" )  {
    echo  "the version is 1.23" ;
}

//  This is not necessary ...
if  ( $show _separators  ==  TRUE )  {
    echo  " ;
}

// .. Because you can use the following simple way:
if  ( $show _separators )  {
     echo  " ;
}
?

Convert to a Boolean value

To explicitly convert a value to a boolean, use either (bool) or (Boolean) to cast. However, there are many cases where casting is not required because the value is automatically converted when an operator, function, or process control structure requires a boolean parameter.

See also type-trick.

When converted to Boolean , the following values are considered FALSE:

• The Boolean value of FALSE itself
• The integer value 0 (0)
• The floating-point value 0.0 (0)
• An empty string, and the string "0"
• An array that does not include any elements
• Objects that do not include any member variables (PHP 4.0 only applies)
• Special type NULL (including variables that have not been set)
• SimpleXML object generated from an XML document without any tags (tags)

All other values are considered TRUE(including any resources).