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AVR studio doubt wrong result

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Embedded_Geek

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Can anyone please explain why the result of the operation given below is always wrong

unsigned long var = 0;

var = 10*9600;

The result comes as 30464. I have even tried by changing the data type of "var" to double.


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Embedded_Geek said:
Can anyone please explain why the result of the operation given below is always wrong

unsigned long var = 0;

var = 10*9600;

The result comes as 30464.
Click to expand...

Try this:

Code: 
var = 10ul*9600ul;

That should work.
 
Thank you very much alexxx. It worked fine as you said but can you explain me why 10*9600 is not working. I mean I have used this kind of statements in IAR, RIDE etc.
 

Embedded_Geek said:
can you explain me why 10*9600 is not working. I mean I have used this kind of statements in IAR, RIDE etc.
Click to expand...
I also do not have such problems in IAR. GCC is an older and more "strict" compiler. The problem is that when the compiler sees raw numbers < 65536, then it interprets them as 16-bit.
So 10*9600 = 96000 = 0x17700.
But since this result is interpreted as 16-bit, then the remaining result will be 0x7700 = 30464. You have to use this "ul" to declare that this is an unsigned long value.

Depending on the value you can use ui for 16-bit, ul for 32-bit and ull for 64-bit values.

Alexandros
 
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