Every programming language has its own set of data types that help
developers to write programs. A data type is a classification of data .
This could mean categorizing the the type of data as an amount of money,
time or percentage. In PHP the data type can be broadly classified as
scalar and compound data types.
Scalar data type
Four type of data comes under the category of scalar data type: Boolean, integer, float and string.
The Boolean data type can either be
true or false.
The numeric representation of the Boolean data type is 1 for true and 0
for false. The the fallowing example uses this data type:
$myVal = True; // Boolean variable type.
An integer data type consist of numbers. You can use both negative or
positive numbers like [...-2,-1,0,1,2,3,...]. The size of an integer in PHP solely
depends on the operating system that you are using. typically , the size
of an integer can be up to 2 billion. In the fallowing code, $myVal is an
integer type variable with a value of 9:
$myVal =9; //Is an integer.
A float is a data type that is also use for storing numbers.
floats are use to express decimal numbers, you can use the integer
data type for non decimal numbers. Floats are also known as doubles or
real numbers and have a precision of up 14 decimal places. In the
fallowing code ,$floatVal is a float type variable and has a value of
$ floatVal = 9.98765 // Is a float type variable
A string can be best defined as a series of characters. In PHP, a
character is nothing but a byte. There are 256 different types of
characters that can be used in strings. There is no maximum limit
specification in relation to strings to PHP; therefore you need not worry
about a very long string .There are two ways to specify a string
discussed on fallowing sections.
You can use single quotes to specify a simple string. How ever when a
string is enclosed in single quotes and it also contains some text
enclosed in double quotes, you must use the backslash escape character
to escape the single quotes. In other wards when you don't want to parser
to treat single quotes as syntax and display them as part of the output
of the code, you need o use a back slash before the single quotes.
Lets consider a simple example to understand how single quotes are used
to specify a string:
echo 'This is my First String'; // will print the string on the screen.
Now consider an example where double quotes are used within
single quotes and single quotes is represent in the text enclosed in
echo 'Rishi says: "I'm doing well "'; , //will display error.
When you try to execute this statement, an error message will appear on
the screen. This is because when you use a single quote within double
quotes, you need to escape the single quote with a backslash. In the
fallowing statement is written correctly:
echo 'Rishi says: "I\'m doing well "'; , //is Correct now.
The output will be Rishi says: "I'm doing well".
Another thing that you should remember when using single quoted string
is that such string don't support variable expansion: If you use a name
of variable within single quote and try to print the value of a
variable, the name of the variable will be printed instead of its
value. Consider the fallowing example:
echo 'Hello $name';
The output will be Hello $name
The correct syntax is
echo "Hello $name";
The output will be Hello Rishi.
A double quoted strings supports several other escape characters as
: new line
: Horizontal tab
: Dollar sign
: Double quote