Introduction to PHP – Part2


Data Types:

PHP supports eight primitive types; four scalar types two compound and two special types. In this section we will discuss scalar types; boolean, integer, float and string. Other four array, object, resource and null will be discussed in the later sections.


 To define boolean variable we can specify TRUE or FALSE, both are case insensitive. The size of the Boolean variable is one byte.

Example# 1:

$flag = True; // assign the value TRUE to $flag
Echo $flag; // Output will be 1, which means TRUE


According to PHP manual an integer is a number of set Z = {…, -2, -1, 0, 1, 2, …}. In general integer is a positive or negative number without decimal point. Integer can be specified in decimal, hexadecimal or octal notation. The sign (+ or -) is optional. If the integer is precede by number 0(zero), it is octal notation and 0X is hexadecimal notation. The size of integer is platform dependent and maximum size is four bytes. If a number greater than integer range is encountered, PHP interpret it as float.

Example# 2

$decimal = 4532; // positive decimal number
$negatige = -320; // negative decimal number
$Octal = 770; // octal number (equivalent to 504 decimal)
$Hex = 0x3F; // hexadecimal number (equivalent to 63 decimal)

Note that there is no integer division is available in PHP, the result is always float.


Floating point numbers are the real number with decimal point. They are also known as doubles.  The size of float is platform dependent, the maximum size is eight bytes with a precision of roughly 14 decimal digits.

Example# 3

$x = 5.362; // floating point number
$y = 2.3e2; // can also be expressed in e notation
$z = 2E-10; // another form of float representation


A string variable is used to store array of characters or character strings. For instance, if we need to store characters “ABCD” in a variable, string is required. A string can also contain numbers, space and special characters and should enclose by quote. PHP supports a string of any size, the limit depends upon the memory of the computer on which PHP is running.

The following example creates a string variable called $myString, assign string “Hello World” to the string and finally prints $myString to the monitor.

Hello World

Example# 4

$myString="Hello World";
echo $ myString;

The output of the above code will be

Hello World

A string can be specified in four ways.

  • Single quoted
  • Double quoted
  • heredoc syntax
  • now doc syntax

We will discuss string in detail in following tutorials.

About the Author:

Bhoj R Dhakal is a programmer. He has few years of experience in software development and maintenance. He has published series of PHP tutorials for webanddesigners.