PHP - Variable Types
The main way to store information in the middle of a PHP program is by using a variable.
Here are the most important things to know about variables in PHP.
- All variables in PHP are denoted with a leading dollar sign ($).
- The value of a variable is the value of its most recent assignment.
- Variables are assigned with the = operator, with the variable on the left-hand side and the expression to be evaluated on the right.
- Variables can, but do not need, to be declared before assignment.
- Variables in PHP do not have intrinsic types - a variable does not know in advance whether it will be used to store a number or a string of characters.
- Variables used before they are assigned have default values.
- PHP does a good job of automatically converting types from one to another when necessary.
- PHP variables are Perl-like.
PHP has a total of eight data types which we use to construct our variables −
Integers −
are whole numbers, without a decimal point, like 4195.
Doubles −
are floating-point numbers, like 3.14159 or 49.1.
Booleans −
have only two possible values either true or false.
NULL −
is a special type that only has one value: NULL.
Strings
− are sequences of characters, like 'PHP supports string operations.
Arrays −
are named and indexed collections of other values.
Objects −
are instances of programmer-defined classes, which can package up both other kinds of values and functions that are specific to the class.
Resources −
are special variables that hold references to resources external to PHP (such as database connections).
