Boolean

In PHP, “bool” is one of the built-in scalar data types. It is used to express the truth value, and it can be either True or False. A Boolean literal uses the PHP constants True or False. These constants are case-insensitive, in the sense, true, TRUE or True are synonymous.

You can declare a variable of bool type as follows −

$a=true;

Example

Logical operators (<, >, ==, !=, etc.) return Boolean values.

Open Compiler

<?php
   $gender="Male";
   var_dump ($gender=="Male");
?>

It will produce the following output −

bool(true)

Boolean Values in Control Statements

Boolean values are used in the construction of control statements such as if, while, for and foreach. The behaviour of these statements depends on the true/false value returned by the Boolean operators.

The following conditional statement uses the Bool value returned by the expression in the parenthesis in front of the if keyword −

$mark=60;if($mark>50)echo"pass";elseecho"fail";

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Converting a Value to Boolean

Use the (bool) casting operator to convert a value to bool. When a value is used in a logical context it will be automatically interpreted as a value of type bool.

A non-zero number is considered as true, only 0 (+0.0 or -0.0) is false. Non-empty string represents true, empty string “” is equivalent to false. Similarly, an empty array returns false.

Example

Take a look at this following example −

Open Compiler

<?php
   $a = 10;
   echo "$a: ";
   var_dump((bool)$a);

   $a = 0;
   echo "$a: ";
   var_dump((bool)$a);

   $a = "Hello";
   echo "$a: ";
   var_dump((bool)$a);

   $a = "";
   echo "$a: ";
   var_dump((bool)$a);

   $a = array();
   echo "$a: ";
   var_dump((bool)$a);
?>

It will produce the following output −

10: bool(true)
0: bool(false)
Hello: bool(true)
: bool(false)
Array: bool(false)