Inspiration was provided by various user comments and by the work over atīefore utilizing these tables, it's important to understand types and their Supplemental is also related to the manual section on Operators, for both loose and strict comparisons. The following tables demonstrate behaviors of PHP e.Getting Started Introduction A simple tutorial Language Reference Basic syntax Types Variables Constants Expressions Operators Control Structures Functions Classes and Objects Namespaces Enumerations Errors Exceptions Fibers Generators Attributes References Explained Predefined Variables Predefined Exceptions Predefined Interfaces and Classes Predefined Attributes Context options and parameters Supported Protocols and Wrappers Security Introduction General considerations Installed as CGI binary Installed as an Apache module Session Security Filesystem Security Database Security Error Reporting User Submitted Data Hiding PHP Keeping Current Features HTTP authentication with PHP Cookies Sessions Dealing with XForms Handling file uploads Using remote files Connection handling Persistent Database Connections Command line usage Garbage Collection DTrace Dynamic Tracing Function Reference Affecting PHP's Behaviour Audio Formats Manipulation Authentication Services Command Line Specific Extensions Compression and Archive Extensions Cryptography Extensions Database Extensions Date and Time Related Extensions File System Related Extensions Human Language and Character Encoding Support Image Processing and Generation Mail Related Extensions Mathematical Extensions Non-Text MIME Output Process Control Extensions Other Basic Extensions Other Services Search Engine Extensions Server Specific Extensions Session Extensions Text Processing Variable and Type Related Extensions Web Services Windows Only Extensions XML Manipulation GUI Extensions Keyboard Shortcuts ? This help j Next menu item k Previous menu item g p Previous man page g n Next man page G Scroll to bottom g g Scroll to top g h Goto homepage g s Goto search.This means ? is same as ( !isset() || is_null() ).So, it always returns first parameter, unless first parameter happens to be NULL.? is like a "gate" that only lets NULL through.The comment on each line shows the result. Ran the below on php interactive mode ( php -a on terminal). Would then have $a be equal to false and $b equal to 'g'. Once it's no longer null, then you end up with differences in that the ? operator would always return the first argument while the ?: shorthand would only if the first argument was truthy, and that relies on how PHP would type-cast things to a boolean. Of course, this is always assuming the first argument is null. However, even with the notice, PHP will give the same response back. The lines that have the notice are the ones where I'm using the shorthand ternary operator as opposed to the null coalescing operator. Print $b ?: 'e' // Notice: Undefined index: c in /in/apAIb on line 33 Here's some example code to demonstrate this: null) It returns its first operand if it exists and is not NULL The null coalescing operator (?) has been added as syntactic sugarįor the common case of needing to use a ternary in conjunction with The PHP 7.0 migration docs has this to say: When your first argument is null, they're basically the same except that the null coalescing won't output an E_NOTICE when you have an undefined variable. $result = isset($var) ? $var : 'default' Or the second argument otherwise $result = $var ? 'default' Null coalescing ? returns the first argument if it's set and is not null. Or the second argument otherwise $result = $var ?: 'default' Elvis ?: returns the first argument if it contains a "true-ish" value (see which values are considered loosely equal to true in the first line of the Loose comparisons with = table).
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