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The Big "Why equal doesn't equal" Quiz

The Big "Why equal doesn't equal" Quiz

Presented on April 14th 2018 at the Bulgarian Web Summit, Sofia, Bulgaria.
https://bulgariawebsummit.com/
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Partial slide deck - the actual quiz will not be made public.
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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.
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Links:
http://phpcheatsheets.com/
https://github.com/jrfnl/PHP-cheat-sheet-extended

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

Juliette Reinders Folmer

April 14, 2018
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Transcript

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

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  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

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  3. View Slide

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

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  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 ) {}

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  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() ) {}

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  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

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  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

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

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  10. Want to know more ?

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

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