On Fri, Aug 19, 2011 at 11:32 AM, Geo Gkolfin <geo198...@gmail.com> wrote:
> Thanks for your answer!
> Actually it almost worked!
> %lu prints 3354000128 instead of 3354000112.
> %lx prints c7e9fb00 which is 3354000128 hex.
> This can drive you crazy! Any ideas please?
>
Without explicitly stepping through the code and seeing what it is doing, we
would be guessing.
>
> On Thu, Aug 18, 2011 at 12:58 AM, Michael Schippling <sc...@santafe.edu>wrote:
>
>> That is a little odd...
>>
>> I guess the implicit casting is trying to help you by
>> returning the largest value for the uint16 when converting
>> from a too-big float. When you change to uint32 you
>> should get 0xC7E9FAF0 in your integer (which is what
>> my Widows calculator shows as the correct conversion
>> for decimal 354000112). Then, because the top bit is
>> set and you asked for a signed decimal output "%ld"
>> you should get a negative value, but it's off by 16...
>> -940967168d == 0xC7E9FB00
>> so I'm not sure what is going on.
>>
>> Try printing %lu or %lx and see what you get.
>>
>> MS
>>
>> Geo Gkolfin wrote:
>>
>>> Hello!
>>>
>>> I am using telosb motes and tinyos-2.1.0. I have an application in which
>>> some floating point operations are done and I wish to print (using
>>> PrintfClient) only the decimal part of the result. Since the printed value
>>> is not what it should be -it is always 65535- I wrote a simple program where
>>> I have:
>>>
>>> float y;
>>> uint16_t x;
>>>
>>> y=4354.542134509;
>>> x=y;
>>> printf("int(4354.542134509)=%**u\n",x);
>>> printfflush();
>>>
>>> I run
>>> java net.tinyos.tools.PrintfClient -comm serial@/dev/ttyUSB0:telosb
>>>
>>> and I get the 4354!
>>>
>>> If I change the value stored in y to:
>>> y=3354000112.542134509 then the printf returns 65535 -the same value as
>>> in my application! So I guess this is because the value does not "fit" into
>>> a uint16_t. I change x definition to uint32_t and %u to %ld (make is okay
>>> with that), but then the printed value is -940967168!
>>> What is the problem?
>>>
>>> Thanks in advance,
>>> Georgia
>>>
>>>
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>>
>
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--
Eric B. Decker
Senior (over 50 :-) Researcher
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