Variables, References, and Constants

<< PHP Tutorials - Herong's Tutorial Examples

This chapter provides tutorial notes and example codes on PHP variables, references, and constants. Topics include how to name variables; assigning data values to variables; creating the reference of a variable; using variable variable names; using string expressions as variable names; defining constant names to values; retrieving the value from a constant.

Variables and Assignment Operations

References and Variables

Variable Variable Name - Name Variables with Expressions

Constant and define() Function

Conclusion:

• PHP variables are typeless. Values of different data types can be assigned to the same variable.
• PHP variable names starts with $ sign.
• & operator returns the reference of a variable.
• The reference of a variable can be assigned to a new variable to make an alias to the original variable.
• A variable name can represented as a string expression. This is called variable variable name.
• Functions define() defines a constant with the constant name and the constant value.
• Only scalar data type values can be used as constant values.