help with enum

help with enum

[M.Fayezur Rahman]

Hi Experts,
I was wondering if anyone could please tell me how to
set the size of a enum type. I think by default it is
long (4 bytes). I need to change it for a different
size, for example to int(2 bytes). 

typedef enum {sun=30000, mon, tues, wed, thurs} eTest;
int main(void)
{
	printf("Size is %d",sizeof(eTest));
	return 0;	
}

right now it would print out "Size is 4". I need to
configure it so that it treats enum as a 2 byte int,
therefore print "Size is 2".

Thanks in advance for your help
Raman

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Re: help with enum

[Eljay Love-Jensen]

Hi Raman,

An enum is supposed to be set to an int or an unsigned int (i.e., a machine word).

Some compilers take liberties, and will resize an enum to a {signed|unsigned|nonsigned} char size, or {signed|unsigned} short int size, or even {signed|unsigned} long int size.

Other compilers, have an extension to specify the storage size, such as "enum short Foo { one, two, three };" ... but that is definitely non-portable.

GCC has the -fshort-enums flag, which gives a little extra control over enum sizes.  But it has a sweeping effect.

But by and large, and if you value C/C++ portability, presume that all enums are int or unsigned int sized (machine word sized).

In C++, if that is unacceptable, consider using const values.  That will give you more specific and portable control over the actual size of the enumerations.

HTH,
--Eljay