Re: [Xen-users] uhmm..

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> I see in tools for 3.1 build from source
>
>
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> The file xc_core.c
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> Make error


What is the make error you see?


>
> I think :
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>
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> if ( x +y) < (x) then …..
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>
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> in what case x+y are minor of x ??
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>
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> example:
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> 10 + 0 < 10  in which kind of mode x+y are minor of x … never J

Two things spring to mind:

* if y was negative then you could have x+y < x
* if x fits within the valid range of positive integers but adding y causes an 
overflow, then in C you could find x+y < x

> and the follow example:
>
> if(class->num)
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> return null;
>
> class-num=num;
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>
>
> are wrapping
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> if(class->num)return null; in the same line
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>
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> not in 2 lines
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> because the compiler think that the third line are part of if()

That's OK in C: if you're not using braces { }, then the code controlled by 
the if block ends after the semicolon ; - it should be OK, no matter what 
line it is on.

C doesn't take much notice of where the whitespace (spaces, tabs, new lines) 
is - it breaks things up using braces and semicolons.  In Python, the 
whitespace is very important so this would be more of an issue (in fact, we 
have had issues of the kind you suggest in the Python code in the past).

Cheers,
Mark

>
> sorry for my English
>
>
>
> happy c++
>
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-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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