thanx i got it :)
On Sat, Jul 2, 2011 at 1:57 PM, santosh mahto <santoshbit2...@gmail.com>wrote:
> this will help
>
> ->sizeof operator only need declaration not definition.since sizeof
> operator calculates size at
> compile time.
> At compile time code doesnot seek for definition.it only need
> declaration.if any variable is declared with extern,it thinks that
> its definition will be found at linking time.
>
> In ur question:
> 1 case. when a =20 is done compiler see that its value is declared.so its
> OK .but at link time since def of a is not found
> so linker error. since linker tries to find the actual memory address where
> the def of a is.
>
> see after compilation the symbol table for a will be as
>
> symbolname| memory location| value
> a |find later(garbage)| 20
>
> so there is no problem with compiler .but at link time garbage value need
> to be filled with actual memory address
> since def is not there so linker error.
>
> case2. there will be noentry in the symbol table for a. as code doesnot
> include any defintion related operation.
>
>
> iF anything helps you, dont forget to say thanks
>
> Thanks
> Santosh
>
>
>
>
>
> On Sun, Jul 3, 2011 at 1:38 AM, HARSH PAHUJA <hpahuja.mn...@gmail.com>wrote:
>
>> will ny1 xplain this extern concept....
>> y this is a linker error?
>>
>>
>> On Sat, Jul 2, 2011 at 12:49 PM, HARSH PAHUJA <hpahuja.mn...@gmail.com>wrote:
>>
>>> @piyush plz explain how are u getting this......
>>>
>>>
>>> On Sat, Jul 2, 2011 at 12:10 PM, Piyush Sinha
>>> <ecstasy.piy...@gmail.com>wrote:
>>>
>>>> i) [Linker error] undefined reference to `a'
>>>>
>>>> ii) 4
>>>>
>>>> On 7/3/11, HARSH PAHUJA <hpahuja.mn...@gmail.com> wrote:
>>>> > 1)
>>>> > #include<stdio.h>
>>>> > int main()
>>>> > {
>>>> > extern int a;
>>>> > a=20;
>>>> > printf("%d",sizeof(a));
>>>> > return 0;
>>>> > }
>>>> >
>>>> > 2)
>>>> > #include<stdio.h>
>>>> > int main()
>>>> > {
>>>> > extern int a;
>>>> > printf("%d",sizeof(a));
>>>> > return 0;
>>>> > }
>>>> >
>>>> >
>>>> >
>>>> > --
>>>> > HARSHIT PAHUJA
>>>> > M.N.N.I.T.
>>>> > ALLAHABAD
>>>> >
>>>> > --
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>>>> >
>>>>
>>>>
>>>> --
>>>> *Piyush Sinha*
>>>> *IIIT, Allahabad*
>>>> *+91-8792136657*
>>>> *+91-7483122727*
>>>> *https://www.facebook.com/profile.php?id=100000655377926 *
>>>>
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>>>>
>>>
>>>
>>> --
>>> HARSHIT PAHUJA
>>> M.N.N.I.T.
>>> ALLAHABAD
>>>
>>>
>>>
>>
>>
>> --
>> HARSHIT PAHUJA
>> M.N.N.I.T.
>> ALLAHABAD
>>
>>
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>
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--
HARSHIT PAHUJA
M.N.N.I.T.
ALLAHABAD
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