Php-manual Learning----"Language Reference"----"Type"-----"Boolean type"

July 20, 2017 15:41:26
Boolean Boolean type
1. This is the simplest type. Boolean expresses the truth value, which can be TRUE or FALSE. is actually a true and false problem.
2. Syntax
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
?>
3. Typically, the Boolean result returned by the operator is passed to the control flow.
4. To explicitly convert a value to 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.
5. When converting to Boolean, the following values are considered FALSE:
? The Boolean value FALSE itself
? Integer value 0 (0)
? 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 assigned)
? SimpleXML object generated from an empty tag
6. For example:
<?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)
?>
Summary: Booelan values are typically used in process control, what is true when executed, and what is performed when false.

Php-manual Learning----"Language Reference"----"Type"-----"Boolean type"