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In PHP, the string "1" equals the string "+1" unless you do a strict comparison (===).

echo ("1" == "+1") ? "equals" : "not equals"; // result: "equals"

I'd prefer not to do a strict comparison, because the string "1" might be provided as an integer 1 in this case. I cannot do intval() to distinguish them because both return as 1, and I cannot do is_numeric() to distinguish them because both return true.

So, two questions please:

  1. Is there any way to differentiate between these other than to convert the input to strings via strval() and use strict comparison?

  2. Is this a bug or intended behavior in PHP? The reason doesn't seem mathematical ("2" does not equal "1+1" for instance, although "2" does equal "+2"). I'm curious as to the reasoning behind this.

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    Seems a bit contradictory what you want… :) You want loose comparison but not quite as loose as PHP defaults to…? Commented Feb 28, 2017 at 16:34
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    What about a pragmatic ((string)"1" === "+1") or ((string) intval("1") === "+1")? Commented Feb 28, 2017 at 16:34
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    "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. " - PHP Docs Commented Feb 28, 2017 at 16:35
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    Mathematically, one and positive one are equivalent, that's basically what you're seeing. I'm not sure why you would prefer to not do a strict comparison here. Commented Feb 28, 2017 at 16:35
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    @nickb, thank you, that's what I was missing. I didn't see how "+1" could be considered a number unless it was mathematical (PHP treating it like "0+1"), but of course, it's positive one. I wish I had thought of that. Commented Feb 28, 2017 at 17:08

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When using == instead of === a loose comparison is used.

This often leads to types using truthyness when comparing incomparable types

have a look a the manual here to see the table of comparison http://php.net/manual/en/types.comparisons.php

even though "+1" is not mentioned, it would be handled similarly to a '-1'

If you don't want this to happen, you do need to use ===

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