Variables in PHP
In part 2 we are going to deal with Data Types and
Type Casting amongst other things.
Data Types
These are the data types which uses .
- string ( text )
- integer (numeric)
- double(numeric)
- array
- object
- unknown type
As you can see there are not as many data type are
there are in some other languages , this in fact is
a help to many a programmer . As a programmer you do
not worry about setting these data types , PHP does
it for you.
Strings
This is the data type that stores text , this can be
single characters , words and even complete sentences
. How many strings do you think we have below .
$mywages = "not much";
$intloan = "3000";
If you said one you are wrong , if you said two give
yourself a pat on the back . remember we enclosed the
number with quotation marks so PHP treats this as text
information .
Concatenation
This means adding one string to another . If you are
coming from another programming language this may (will)
catch you out from time to time . In PHP we use the
period ( . ) to concatenate strings.For example
$firstname = "Bill";
$secondname = "Gates";
echo $firstname . $secondname;
would print on the screen BillGates
Numeric Values
There are 2 different types of numerical data types
in PHP , integers and doubles. Integers are basicly
whole numbers and doubles are fractional (floating point
) numbers . Here are some examples .
$firstint = 9;
$firstdouble = 23.67;
$secondint = - 76;
$seconddouble = -1239.7432;
The values these types can hold is platform specific
but for example the range for an integer is commonly
-32768 to 32767 on Windows machines.
Type Casting
As you are aware PHP automatically decides what data
type but you do have the option of specifying this yourself
. Here is how you can do this .
$luckynumber = 7;
$lucknumber = (string) $luckynumber;
This would give us a string rather than the integer
we had previously.
Using gettype and settype functions
These are two functions provided with PHP which help
us to determine the data type and set the data type
respectively , lets look at examples of both . Firstly
settype which will display the data type of the variable
<?php
$myname = "Iain";
echo gettype($myname);
?>
string
Now for settype , this allows you to set the data type
. The first parameter is the actual variable , the second
is the data type you require) . In this example we set
the data type and then use gettype to show it has changed.
<?php
$wages = 1000;
settype($wages, "string");
echo gettype($wages);
?>
string
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