PHP Variables and Data Types

Review of Previous Topics

• Discussed PHP syntax.
• Importance of practical experience in writing PHP code.

Setting Up the Environment

1. Open Your Editor
   • Essential to have your code editor open.
2. Start XAMPP
   • Open XAMPP software.
   • Start Apache and MySQL server.
3. Access Your Website
   • Go to your browser and type localhost.
   • Locate your website's folder in the htdocs directory.
   • Select the website created in the first episode.

Mixing HTML with PHP

• Embedding PHP in HTML:
  • Create HTML elements and embed PHP code.
  • Example:

    <p>This is a paragraph.</p>
    <?php echo 'This is also a paragraph.'; ?>
    

  • Refresh browser to see combined output.

Introduction to Variables

• Definition of a Variable:
  • A variable is a memory location in an application that stores data.
  • Conceptualize as a box with a label for easy reference.
• Declaring Variables in PHP:
  • Use a dollar sign ($) to declare a variable.
  • Example:

    $name = 'Danny Crossing';
    

  • Use echo to output variable values.

Naming Conventions for Variables

• Begin variable names with a letter or underscore.
• Use camel case for multiple words:
  • Example: $fullName.
• Subsequent words should start with a capital letter.
• Can include numbers and underscores after the first character.

Data Types in PHP

Scalar Types

1. String:
   • Text data.
   • Example: $string = 'Daniel';
2. Integer:
   • Whole numbers.
   • Example: $number = 42;
3. Float:
   • Decimal numbers.
   • Example: $floatNum = 2.5678;
4. Boolean:
   • True or false values.
   • Example: $isTrue = true;
   • 1 is treated as true, 0 as false.

Array Types

• Definition:
  • A variable that holds multiple values.
• Creating Arrays:
  • Two methods:
    1. array() function:

       $names = array('Daniel', 'Bella', 'Theta');
       

    2. Square brackets (PHP 5.4+):

       $names = ['Daniel', 'Bella', 'Theta'];
       

Object Type

• Definition:
  • An instance of a class.
  • Example:

    $car = new Car();
    

• Not covered in depth until later.

Default Values for Uninitialized Variables

• Default values:
  • String: '' (empty string)
  • Integer: 0
  • Float: 0.0
  • Boolean: false
  • Array: []
  • Object: null
• Always initialize variables to avoid warnings.

Practical Example of Using Variables

1. Declare a variable:

   $name = 'Danny Crossing';
   

2. Use in HTML:

   <p>Hi, my name is <?php echo $name; ?> and I'm learning PHP.</p>
   

• Output combines static and dynamic data.

Conclusion

• It's normal to feel overwhelmed with information.
• Practice is essential for understanding and remembering concepts.
• Future lessons will provide practical examples to reinforce learning.