Parsing the Boolean type of PHP data type (Boolean)

This is the simplest type. boolean expresses a truth value and can be TRUE or FALSE.

Syntax

To specify a Boolean value, use the keywords TRUE or FALSE. Both are not case sensitive.

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

Usually the boolean value returned by the operator will be passed to the control flow.

<?php
// == 是一个操作符，它检测两个变量是否相等，并返回一个布尔值
if ($action == "show_version") {
   echo "The version is 1.23";
}
// 这样做是不必要的...
if ($show_separators == TRUE) {
   echo "<hr>\n";
}
// ...因为可以使用下面这种简单的方式：
if ($show_separators) {
   echo "<hr>\n";
}
?>

Convert to Boolean

To explicitly convert a value to boolean, use (bool) or (boolean) to cast. But in many cases, casting is not necessary because when an operator, function, or flow control structure requires a boolean parameter, the value is automatically converted.

See the identification of type conversion.

When converted to boolean, the following values ​​are considered FALSE:

• Boolean value FALSE itself

• Integer value 0 (zero)

• Floating point value 0.0 (zero)

• The empty string, and the string "0"

• An array that does not include any elements

• An object that does not include any member variables (only applicable to PHP 4.0)

• Special type NULL (including variables that have not been assigned a value)

• SimpleXML objects generated from XML documents without any tags

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

Warning

-1, like other non-zero values ​​(positive or negative), is considered TRUE!

<?php
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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