PHP sports a cool feature called automatic data typing. A PHP developer
can claim variables and use them in most common situations without
having to claim the data type that the variable is. But this is also a
double edged sword because as a developer gets more advanced they may
create functions or scripts that only accept one data type, and throw
errors if you feed it a different type. But that is usually only in the
most complex of PHP applications.
For instance, if my imported script and function is expecting an
integer type variable and I feed it a string type, I will get an error
and know that I must not try to feed it a string... it needs an integer
type variable. No big deal, I will just make sure a number type variable
is all that gets sent through that mechanism.
Here are the data types:
Boolean,
Integer,
Floating
Point Number,
String,
Array,
Object,
Resource,
Null
<?php
// Boolean... true or false data types
$userChoice = true;
// Integer.... whole numbers
$num1 = 3;
// Floating Point Numbers
$num2 = 8.357
// String... a set of alphanumeric characters
$string1 = "Hello World, I just turned 21!";
// Array... we cover building arrays in later lessons
$my_friend_array = array(1 => 'Joe', 2 => 'Adam', 3 => 'Brian', 4 => 'Susan', 5 => 'Amy', 6 => '0', 7 => 'Bob');
// Object...
// Objects work with classes, which we will cover later
// Resource...
// A special variable, holding a reference to an external resource.
// Resources are created and used by special functions.
// Null... value for missing, empty, or unset variables. If null... it has no value and is not set.
$var1 = NULL; // Casting a variable to null will remove the variable and unset its value
?>
PHP has functions to test whether or not a variable is a certain "type".
This is known as the
is_* function family.
<?php
// set the variable and its value
$myVar = "Adam Khoury";
// Run simple if and else statement to see if it is a string or not
if (is_string($myVar)) {
echo "Yes";
} else {
echo "No";
}
?>
Yes
