PHP Data Types

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Online resources

• PHP.net
• W3Schools PHP
• Tutorials Point

Key concepts to understand

• Variables

  • Variable naming rules
    • start with $
    • contain letters, numbers, underscores; no spaces
    • are case-sensitive
  • How to set and get values

• Strings

  • Single-quoted, double-quoted
  • String concatenation
  • String interpolation / variable parsing PHP.net

• Integers

  • Difference between integers and floating point numbers
  • Arithmetic operators: +, -, *, /, ()

• Floating point numbers

  • Difference between integers and floating point numbers

• Arrays

  • Defining with array() or []
  • Comma-delimited
  • Zero-indexed
  • Always maintained in the same order
  • How to set and retrieve values

• Associative arrays

  • Syntax and key/value pairs
  • Array keys must be unique
  • How to set and retrieve values

• Booleans

  • true or false

• Null

  • used to indicate nothing or "no value set"
  • different than 0, "", or false
  • explain how to use isset() and empty()
  • considered empty: null, [], "", false, 0, 0.0, "0"
    • using empty() incorrectly is a common source of PHP bugs

• Constants

  • How to define them