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In PHP, can someone explain to me why this resolves to true:

'NONE' == 0
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Because any non-numerical string cast to int will turn into 0.

If you don't want that to happen, use ===, the identical operator.

Read:
http://php.net/manual/en/language.operators.comparison.php
http://php.net/manual/en/types.comparisons.php

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2 Comments

This is just nitpicking, but is_numeric('16 foo') is FALSE, e.g. a non-numerical string and typecasting it to int will turn it into 16, not 0.
not in this case :) it's all described at de.php.net/manual/en/…
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Because the string is 0 when evaluated in a number context. Quoting:

If you compare a number with a string or the comparison involves numerical strings, then each string is converted to a number and the comparison performed numerically.

So it depends on what the string contains.

Also, see the chapter on Type Juggling and Type Comparison in the PHP Manual.

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As described here: php.net/manual/en/…
so ... NONE is a keyword? Like 'false'? (I'm asking this while reading the chapter)
@Putr no, its a string. nothing more.
@Putr Not really. Any string in a boolean context evaluates to true. So ('false' == false) is false, ('false' == true) is true.
@NullUser it's not a boolean context here though, but a numeric one, so ('10' == 10) and ('0xFF' == 255) and ('16 foo' == 16) is all true.

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