The Big "Why equal doesn't equal" Quiz

Presented on April 14th 2018 at the Bulgarian Web Summit, Sofia, Bulgaria.
https://bulgariawebsummit.com/
---------------------------------------------------------------
Partial slide deck - the actual quiz will not be made public.
---------------------------------------------------------------
So you think you know PHP? But do you really?

We all compare and test data on nearly every other line in our code, be it input validation, an if-statement, a switch or determining what to display and how. So of course we are all experts on how to do these tests and comparisons…. Or are we?

No matter whether you are a beginner or an expert, come and join in the fun for the Big “Why equal doesn’t equal” Quiz, test your knowledge and learn about defensive programming and the quirks of a loose type programming language along the way.
---------------------------------------------------------------
Links:
http://phpcheatsheets.com/
https://github.com/jrfnl/PHP-cheat-sheet-extended

BC Math wrapper: https://gist.github.com/jrfnl/8449978

Transcript

1. The Big
   “Why equal doesn’t equal”
   Quiz
   Presented by:
   Juliette Reinders Folmer
   @jrf_nl
   

   View Slide

2. Who am I?
   • Self- employed independent consultant
   • 15+ years in IT and web development
   • Contributor to LimeSurvey, phpBB, WordPress,
   AdoDB, PHP_CodeSniffer and more
   

   View Slide

3. View Slide

4. Now give yourselves a round of
   applause !!!
   

   View Slide

5. Some best practices (1)
   • Know your variable types and how type juggling
   works ;-)
   • Always use strict checking unless loose checking
   will avoid code duplication
   • Auto-document your code
   DON’T:
   if ( strpos( $x, $y ) ) {}
   DO:
   if ( strpos( $x, $y ) !== false ) {}
   

   View Slide

6. Some best practices (2)
   • Make it a habit to test for type AND for what you
   want to know
   • Non-empty string:
   if ( is_string( $x ) && $x !== ‘’ ) {}
   • Non-empty array:
   if ( is_array( $x ) && count( $x ) > 0 ) {}
   or
   if ( is_array( $x ) && $x !== array() ) {}
   

   View Slide

7. Some best practices (3)
   • Use function_exists(), method_exists() and
   extension_loaded() to write cross-server code
   • Be aware of changes across PHP versions
   • Never be stingy with parentheses ()
   • Avoid $variable contamination
   • isset() and its brother are your friends
   

   View Slide

8. And remember....
   • ... that what you get from $_POST/$_GET/database
   are strings
   • ... that variable and constant names are
   case-sensitive by default
   • ... that switch() does a loose type check
   • ... that calculations with floats can only be done
   reliably by casting to string and using bcmath
   • ... that ctype_ functions are locale() dependent
   • ... that scalar type hints will still juggle variable types
   • ... that strict_types declarations are file-based
   

   View Slide

9. PHPcheatsheets.com
   Contributions welcome:
   https://github.com/jrfnl/PHP-cheat-sheet-extended
   

   View Slide

10. Want to know more ?
    

    View Slide

11. Keep in touch!
    (I’m self-employed, you can hire me ;-) )
    Your feedback is appreciated!
    Slides: speakerdeck.com/jrf
    Contact me: @jrf_nl
    

    View Slide