Difference between revisions of "Understanding PHP Variable Types"

Revision as of 19:23, 25 May 2007

In this chapter we will look at the PHP integer, string, float and boolean variable types. Since the the array and object types are slightly more complex entities we will devote subsequent chapters to them later in the book (see Using Arrays in PHP and PHP Object Orientation).

The PHP Integer Variable Type

Integer variables are able to hold a whole number in the range of -2147483648 to 2147483647. Negaitve values can be asssigned by palcing the minus (-) sign after the assigment operator and before the number. If the value assigned to an integer type variable moves outside the supported range, either via assignment or mathematical calculation, the variable type is automatically converted to a floating point type.

The following examples assign integers to variables:

<?php

$myInteger = 10;

$myNegative = -13457231;

?>

The PHP Float Variable Type

Floating point variables contain numbers that require the use of decimal places. In addition, float variables can store whole numbers up to higher values than the integer variable type (such as 1.067, 0.25, 423454567098, 84664435.9576). Floating point variable creation and intialization examples are as follows:

<?php

$myFloat = 9234.98;

$myOtherFloat = 9547894367.987483701

?>

The PHP Boolean Variable Type

The PHP boolean variable holds a value of true or false and are used to test conditions such as whether some part of a script was performed correctly. We will look at using boolean values in greater detail when we look at PHP Looping and Flow Control. It is useful to know that the true and false values are actually represented internally by PHP as the numbers 1 and 0 respectively.

The PHP String Variable