Booleans

Syntax

To specify a boolean-literal, use either the keyword TRUE or FALSE. Both are case-insensitive.

$foo = True; // assign the value TRUE to $foo     
       

Usually you use some kind of operator which returns a boolean value, and then pass it on to a control structure.

if ($action == "show_version") // == is an operator which returns a boolean
{
    echo "The version is 1.23";
}

// this is not necessary:
if ($show_separators == true)
{
    echo "<hr>\n";
}

// because you can simply type this:
if ($show_separators)
{
    echo "<hr>\n";
}
       

Converting to boolean

To explicitely convert a value to boolean, use either the (bool) or the (boolean) cast. However, in most cases you do not need to use the cast, since a value will be autmatically converted if an operator, function or control-structure requires a boolean-argument.

See also type-juggling.

When converting to boolean, the following values are considered FALSE:

• the boolean FALSE

• the integer 0 (zero)

• the double 0.0 (zero)

• the empty string, and the string "0"

• an array with zero elements

• an object with zero elements

• the special value NULL