Editing PHP Skills Tests (section)

== Language specifications ==

'''Q: What kind of regular expression does PHP include?''' (multiple choice)

<ol style="list-style-type:lower-latin;">
<li>PCRE</li>
<li>Java REGEX</li>
<li>Ruby REGEX</li>
<li>None of the above</li>
</ol>

'''A: (a) PCRE'''

`preg` is a wrapper for the PCRE (Perl-Compatible Regular Expressions) library.

However, an answer submitted to [http://hlam.com.ua/expertrating/question.php?id=12931 the cheaters' site] says the answer is (d) None of the above.

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'''Q: Is the PHP float type guaranteed to be 64 bit IEEE?'''

<ol style="list-style-type:lower-latin;">
<li>yes</li>
<li>no</li>
</ol>

"64 bit IEEE" translates to "double-precision floating-point format," meaning a float value occupies 64 bits (8 bytes) of memory.

* 1 bit for the sign
* 11 bits for the exponent
* 52 bits for the fraction.

From the [http://php.net/manual/en/language.types.float.php PHP documentation]:

<blockquote>'''Although it depends on the system, PHP typically uses the IEEE 754 double precision format''', which will give a maximum relative error due to rounding in the order of 1.11e-16. </blockquote>

Which to me suggests that while you should assume that it's IEEE 754 double precision, it is not in fact ''guaranteed''.