Introduction to PHP: Data Types and Variables

PHP Data Types

• String: Represents a sequence of characters, enclosed in quotes.
• Integer: A non-decimal number, positive or negative, within a specific range.
• Float (Double): A number with decimal points used for precision.
• Boolean: Represents a binary value, either true or false.
• Array: A collection of values stored in a single variable, indexed by keys or numeric indices.
• Object: An instance of a class that can contain properties and methods.

PHP Variable Types Examples

• String: $name = "John";
• Integer: $age = 30;
• Float: $price = 29.99;
• Boolean: $isAvailable = true;
• Array: $colors = array("red", "green", "blue");
• Object: $person = new Person();

PHP Variable Scope Types

• Local Scope: Variables declared within a function, accessible only inside that function.
• Global Scope: Variables declared outside any function, accessible from any part of the script.
• Static Scope: Variables retain their value between function calls, declared with the keyword static.
• Parameter Scope: Variables passed to functions as arguments, limited to the function's context.

PHP Variable Naming Conventions

• Case Sensitivity: Variable names are case-sensitive ($var and $Var are different).
• Starting Character: Must begin with a letter or underscore; cannot start with a number.
• Allowed Characters: Can contain letters, numbers, and underscores; no spaces or special characters.
• Descriptive Names: Use clear, descriptive names for better readability, e.g., $totalCost instead of $tc.

PHP Operators and Their Operations

• Arithmetic Operators: Used for basic math operations (addition, subtraction, multiplication, division).
• Assignment Operators: Assign values to variables, e.g., =, +=, -=, *=.
• Comparison Operators: Compare two values, returning boolean results (==, ===, !=, !==).
• Logical Operators: Combine boolean values (AND, OR, NOT).
• String Operators: Used to concatenate strings, represented by the dot . operator.