Booleans data type in php

This is the easiest type. A boolean expresses a truth value. It can be either TRUE or FALSE.

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

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

// == is an operator which test

// equality and returns a boolean

if ($action == "show_version") {

echo "The version is 1.23";

}

// this is not necessary...

if ($show_separators == TRUE) {

echo "

---

\n";

}

// ...because you can simply type

if ($show_separators) {

echo "

---

\n";

}

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Converting to boolean

To explicitly 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 automatically converted if an operator, function or control structure requires a boolean argument.

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

the boolean FALSE itself

the integer 0 (zero)

the float 0.0 (zero)

the empty string, and the string "0"

an array with zero elements

an object with zero member variables (PHP 4 only)

the special type NULL (including unset variables)

SimpleXML objects created from empty tags

Every other value is considered TRUE (including any resource).

Warning

-1 is considered TRUE, like any other non-zero (whether negative or positive) number!

var_dump((bool) ""); // bool(false)

var_dump((bool) 1); // bool(true)

var_dump((bool) -2); // bool(true)

var_dump((bool) "foo"); // bool(true)

var_dump((bool) 2.3e5); // bool(true)

var_dump((bool) array(12)); // bool(true)

var_dump((bool) array()); // bool(false)

var_dump((bool) "false"); // bool(true)

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