ZEND PHP 5 Certification STUDY GUIDE

PHP Basics ” 11
• When converted to a number or a string, a Boolean becomes 1 if it is true, and
0 otherwise.
Compound Data Types
In addition to the scalar data type that we have just examined, PHP supports two
compound data types—so called because they are essentially containers of other
data:
• Arrays are containers of ordered data elements; an array can be used to store
and retrieve any other data type, including numbers, Boolean values, strings,
objects and even other arrays. They are discussed in the Arrays chapter
• Objects are containers of both data and code. They form the basis of Objectoriented
Programming, and are also discussed in a separate chapter called Object
Oriented Programming in PHP.
Other Data Types
In addition to the data types that we have seen so far, PHP defines a few additional
types that are used in special situations:
• NULL indicates that a variable has no value. A variable is considered to be NULL
if it has been assigned the special value NULL, or if it has not yet been assigned
a value at all—although in the latter case PHP may output a warning if you
attempt to use the variable in an expression.
• The resource data type is used to indicate external resources that are not used
natively by PHP, but that have meaning in the context of a special operation—such
as, for example, handling files or manipulating images.
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)
Converting Between Data Types
As we mentioned, PHP takes care of converting between data types transparently
when a datum is used in an expression. However, it is still possible to force the conversion
of a value to a specific type using type conversion operators. These are sim-