how to implement this ?

[Andrew Haley]

On 01/07/2013 05:39 AM, horseriver wrote:
> On Mon, Jan 07, 2013 at 03:09:31PM +0000, Andrew Haley wrote:
>> On 01/07/2013 05:11 AM, horseriver wrote:
>>> On Mon, Jan 07, 2013 at 02:31:19PM +0000, Andrew Haley wrote:
>>>> On 01/07/2013 04:46 AM, horseriver wrote:
>>>>> hi:
>>>>>
>>>>>   how to implement this assignment by MACRO?
>>>>>   int a,b,c ;
>>>>>   
>>>>>   ((a==0)?b:c)=8;
>>>>
>>>> This is for help with GCC, not general C coding help.
>>>>
>>>> *((a==0) ? &b : &c) = 8;
>>>>
>>>> But this is really horrible code.  I wouldn't do it.
>>>
>>> thans!
>>>   
>>>   why gcc report that error ?
>>>   
>>>   gcc can translate "  ((a==0)?b:c)=8 " into if-else sentence .
>>>
>>>   wht is the reason ？
>>
>> Please supply the test case and the error message.
>>
> 
> ok
> 
> here is this code : 
> 
> #define INPUT_KEYCODE(dev, scancode) ((dev->keycodesize == 1) ? ((u8*)dev->keycode)[scancode] : \
> 			((dev->keycodesize == 2) ? ((u16*)dev->keycode)[scancode] : (((u32*)dev->keycode)[scancode])))
> 
> and here is the callee code :
> 
>         unsigned int keycode ;
> 	
>     	INPUT_KEYCODE(dev, scancode) = keycode;
> 
>         dev is a struct , scancode is a unsigned int
> 
> and gcc report error is :
> 
>         error: lvalue required as left operand of assignment

That is the wrong error.

I need to see the whole of the code that resulted in the error that was
"gcc can translate "  ((a==0)?b:c)=8 " into if-else sentence ."