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Variables & Numeric Data Types

• PHP has eight pre-defined data types: four 'scalar' types (integer, float, string, boolean), two 'composite' types (array, object), and two 'special' types (resource, null).
• An identifier is a name created in PHP code to refer to a particular piece of data.
• The ‘assignment’ of data to an identifier is the process by which the reference, or association, between an identifier and its data value is made.
• A variable is an identifier for which the data value assigned to it can change, or ‘vary’.
• Variable identifiers begin with a $ followed by the variable’s name.
• Variable names are case-sensitive and must start with a letter or underscore followed by any number and combination of letters, underscores, and numbers.
• Static, or 'hard-coded', values assigned to variables are known as literals .
• The integer data type is for representing integral, or whole, numbers.
• Integer literals can be specified in decimal, hexadecimal, or octal notation.
• The float data type is for representing floating-point numbers, or numbers with fractional parts.
• Float literals can be specified as decimal numbers in regular or exponential notation.
• var_dump() is a built-in PHP function that ouptuts the type and value of a variable.
• Additional resources:
  • PHP Manual - Variables
  • PHP Manual - Integer Data Type
  • PHP Manual - Float Data Type
  • Function Reference - var_dump()