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Re: Implied cast differs from explicit cast

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On 1/16/2012 2:42 AM, Arno Welzel wrote:
> Jerry Stuckle, 2012-01-16 04:39:
>
>> On 1/15/2012 10:08 PM, lb wrote:
>>> jstucklex@attglobal.net wrote:
>>>> ...
>>>> No, it is not.  '0x12' is a hex number, not an integer.  (int)'0x12'
>>>> converts this correctly to 0.
>>>
>>> OK, but if (int)'0x12' is 0, why is '0x12'+0 == 18?
>>>
>>> Why are they different? Aren't they both doing 'string conversion to
>>> number'?
>>
>> As I said - '0x12' is a hex value, not an integer.  You are trying to
>> convert it as if it were a string representation of an integer.  The
>> implicit conversion recognizes it is a hex value and uses the
>> appropriate conversion.
>
> There is no difference between "hex value" and "integer" - both 0x12 and
> 18 are just different representations of the same value. The problem is
> that the explizit cast from string to int does not take this into account.
>
> Example:
>
> <?php
> $a = 0x12;
> $b = 18;
> print $a-$b;
> ?>
>
> Result:
>
> 0
>

In C/C++ there is no difference.  However, in PHP there is.  The 'x' is 
not a valid decimal character, so (int) '0x12' returns 0.

The correct function to use when converting hexadecimal strings is hexdec().

-- 
==================
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
==================

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Thread

Implied cast differs from explicit cast lb <lb2048@pobox.com.delete> - 2012-01-16 01:10 +0000
  Re: Implied cast differs from explicit cast Jerry Stuckle <jstucklex@attglobal.net> - 2012-01-15 20:51 -0500
    Re: Implied cast differs from explicit cast lb <lb2048@pobox.com.delete> - 2012-01-16 03:08 +0000
      Re: Implied cast differs from explicit cast Jerry Stuckle <jstucklex@attglobal.net> - 2012-01-15 22:39 -0500
        Re: Implied cast differs from explicit cast Arno Welzel <usenet@arnowelzel.de> - 2012-01-16 08:42 +0100
          Re: Implied cast differs from explicit cast Curtis Dyer <dyer85@gmail.com> - 2012-01-16 09:04 +0000
          Re: Implied cast differs from explicit cast Jerry Stuckle <jstucklex@attglobal.net> - 2012-01-16 08:25 -0500
            Re: Implied cast differs from explicit cast "M. Strobel" <sorry_no_mail_here@nowhere.dee> - 2012-01-16 19:51 +0100
      Re: Implied cast differs from explicit cast The Natural Philosopher <tnp@invalid.invalid> - 2012-01-16 13:28 +0000
        Re: Implied cast differs from explicit cast Jerry Stuckle <jstucklex@attglobal.net> - 2012-01-16 08:45 -0500
          Re: Implied cast differs from explicit cast Arno Welzel <usenet@arnowelzel.de> - 2012-01-17 06:59 +0100
            Re: Implied cast differs from explicit cast Arno Welzel <usenet@arnowelzel.de> - 2012-01-17 07:00 +0100
              Re: Implied cast differs from explicit cast Jerry Stuckle <jstucklex@attglobal.net> - 2012-01-17 08:17 -0500
            Re: Implied cast differs from explicit cast Jerry Stuckle <jstucklex@attglobal.net> - 2012-01-17 08:16 -0500
              Re: Implied cast differs from explicit cast Arno Welzel <usenet@arnowelzel.de> - 2012-01-19 13:36 +0100
                Re: Implied cast differs from explicit cast Arno Welzel <usenet@arnowelzel.de> - 2012-01-19 13:39 +0100
                Re: Implied cast differs from explicit cast Jerry Stuckle <jstucklex@attglobal.net> - 2012-01-19 09:06 -0500
                Re: Implied cast differs from explicit cast Jerry Stuckle <jstucklex@attglobal.net> - 2012-01-19 09:05 -0500
                Re: Implied cast differs from explicit cast The Natural Philosopher <tnp@invalid.invalid> - 2012-01-19 15:01 +0000
                Re: Implied cast differs from explicit cast Jerry Stuckle <jstucklex@attglobal.net> - 2012-01-19 14:41 -0500
  Re: Implied cast differs from explicit cast "M. Strobel" <sorry_no_mail_here@nowhere.dee> - 2012-01-16 09:49 +0100
  Re: Implied cast differs from explicit cast "Álvaro G. Vicario" <alvaro.NOSPAMTHANX@demogracia.com.invalid> - 2012-01-16 11:48 +0100
    Re: Implied cast differs from explicit cast lb <lb2048@pobox.com.delete> - 2012-01-17 02:35 +0000

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