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Bug #39531 soft evaluation between integers and strings
Submitted: 2006-11-16 11:08 UTC Modified: 2006-11-20 00:04 UTC
From: jakobsg at gmail dot com Assigned:
Status: Not a bug Package: Variables related
PHP Version: 4.4.4 OS: All
Private report: No CVE-ID: None
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 [2006-11-16 11:08 UTC] jakobsg at gmail dot com
This is pretty straight forward.
The soft evaluation (==) feature in php can be nice, personally I never use it, but I acknowledge that it can be useful in some situations.
The result of the following evaluation however is not acceptable by any means (even in soft evaluation):

0 == '0'  (true, and acceptable)
0 == 'o'  (true, really!!!)

0 == 'o' are equal ... Common - this can only lead to errors.

Best regards Jakob Simon-Gaarde

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 [2006-11-16 11:15 UTC]
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at and the instructions on how to report
a bug at

 [2006-11-16 21:07 UTC] jakobsg at gmail dot com
Is there some where in particular I should look?

It's not here:
 [2006-11-17 10:49 UTC]
Er -- yes it is. Table O-2, to be specific.
 [2006-11-17 11:56 UTC] jakobsg at gmail dot com
OK, I think you missed the point. It's not the stringified zero ("0") I'm talking about, it's the letter "o" that evaluates true when compared with zero. The letter "o" is no where en the O-2 table. Sorry if we have been talking about apples and bananas :-)
 [2006-11-20 00:04 UTC]
No, I haven't missed the point at all -- you have.  In that table, the last row and last column have the heading "php" which is intended to represent *all* strings except the 3 explicitly mentioned elsewhere -- this would include the string "o".

(This conversion of non-numeric strings to zero is also noted at
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