The Big "Why equal doesn't equal" Quiz - PHP Serbia

Presented on May 26t 2019 at the PHP Serbia conference, Belgrade, Serbia.
https://2019.phpsrbija.rs/
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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

Transcript

1. The Big “Why equal doesn’t equal” Quiz Presented by: Juliette Reinders Folmer @jrf_nl
2. @jrf_nl #PHPSRB Who am I? • Self-employed independent consultant • 15+ years in IT and software development • Contributor to LimeSurvey, phpBB, WordPress, AdoDB, PHP_CodeSniffer and more
4. Now give yourselves a round of applause !!!
5. @jrf_nl #PHPSRB 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 ) {}
6. @jrf_nl #PHPSRB 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() ) {}
7. @jrf_nl #PHPSRB 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
8. @jrf_nl #PHPSRB 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 declarations will still juggle • ... that strict_types declarations are file-based
9. PHPcheatsheets.com Contributions welcome: https://github.com/jrfnl/PHP-cheat-sheet-extended
10. @jrf_nl #PHPSRB Want to know more ?
11. Keep in touch! Rate this talk: joind.in/talk/c89f8 Slides: speakerdeck.com/jrf Contact me: @jrf_nl