PHP provides four primitive data types: integers, floating point numbers, strings, and booleans. In addition, there are two compound data types: arrays and objects.

Integers are whole numbers. The range of integers in PHP is
equivalent to the range of the `long`

data type in
C. On 32-bit platforms, integer values range from -2,147,483,648 to
+2,147,483,647. PHP automatically converts larger values to floating
point numbers if you happen to overflow the range. An integer can be
expressed in decimal (base-10), hexadecimal (base-16), or octal
(base-8). For example:

$decimal=16; $hex=0x10; $octal=020;

Floating point numbers represent decimal values. The range of
floating point numbers in PHP is equivalent to the range of the
`double`

type in C. On most platforms, a double can
be between 1.7E-308 to 1.7E+308. A double may be expressed either as
a regular number with a decimal point or in scientific notation. For
example:

$var=0.017; $var=17.0E-3

PHP also has two sets of functions that let you manipulate numbers with arbitrary precision. These two sets are known as the BC and the GMP functions. See http://www.php.net/bc and http://www.php.net/gmp for more information.

A string is a sequence of characters. A string can be delimited by single quotes or double quotes:

'PHP is cool' "Hello, World!"

Double-quoted strings are subject to variable substitution and escape sequence handling, while single quotes are not. For example:

$a="World"; echo "Hello\t$a\n"; ...

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