-qenum

Pragma equivalent

#pragma options enum, #pragma enum

Purpose

Specifies the amount of storage occupied by enumerations.

Syntax


Option syntax

                 .-intlong-.   
>>- -q--enum--=--+-int-----+-----------------------------------><
                 +-small---+   
                 +-1-------+   
                 +-2-------+   
                 +-4-------+   
                 '-8-------'


Pragma syntax

                         .-intlong-.        
>>-#--pragma--enum----(--+-int-----+--)------------------------><
                         +-small---+        
                         +-1-------+        
                         +-2-------+        
                         +-4-------+        
                         +-8-------+        
                         +-pop-----+        
                         '-reset---'

Defaults

-qenum=intlong

Parameters

1: Specifies that enumerations occupy 1 byte of storage, are of type signed char if the range of enumeration values falls within the limits of signed char, and unsigned char otherwise.
2: Specifies that enumerations occupy 2 bytes of storage, are of type short if the range of enumeration values falls within the limits of signed short, and unsigned short otherwise. Values cannot exceed the range of signed int.
4: Specifies that enumerations occupy 4 bytes of storage, are of type int if the range of enumeration values falls within the limits of signed int, and unsigned int otherwise.
8: Specifies that enumerations occupy 8 bytes of storage. In 32-bit compilation mode, the enumeration is of type long long if the range of enumeration values falls within the limits of signed long long, and unsigned long long otherwise. In 64-bit compilation mode, the enumeration is of type long if the range of enumeration values falls within the limits of signed long, and unsigned long otherwise.
int: Specifies that enumerations occupy 4 bytes of storage and are of type int.
intlong: Specifies that enumerations occupy 8 bytes of storage, as with the 8 suboption, if the range of values in the enumeration cannot be represented by one of int or unsigned int. Otherwise, the enumerations occupy 4 bytes of storage as with the 4 suboption.
small: Specifies that enumerations occupy the smallest amount of space (1, 2, 4, or 8 bytes of storage) that can accurately represent the range of values in the enumeration. Signedness is unsigned, unless the range of values includes negative values. If an 8-byte enum results, the actual enumeration type used is dependent on compilation mode.
pop | reset (pragma only): Discards the current pragma setting and reverts to the setting specified by the previous pragma directive. If no previous pragma was specified, reverts to the command-line or default option setting.

Usage

The tables that follow show the priority for selecting a predefined type. The table also shows the predefined type, the maximum range of enum constants for the corresponding predefined type, and the amount of storage that is required for that predefined type, that is, the value that the sizeof operator would yield when applied to the minimum-sized enum. All types are signed unless otherwise noted.

Table 1. Enumeration sizes and types
	enum=1		enum=2		enum=4		enum=8
	enum=1		enum=2		enum=4		32-bit compilation mode		64-bit compilation mode
Range	var	const	var	const	var	const	var	const	var	const
0..127	signed char	int	short	int	int	int	long long	long long	long	long
-128..127	signed char	int	short	int	int	int	long long	long long	long	long
0..255	unsigned char	int	short	int	int	int	long long	long long	long	long
0..32767	ERROR¹	int	short	int	int	int	long long	long long	long	long
-32768..32767	ERROR¹	int	short	int	int	int	long long	long long	long	long
0..65535	ERROR¹	int	unsigned short	int	int	int	long long	long long	long	long
0..2147483647	ERROR¹	int	ERROR¹	int	int	int	long long	long long	long	long
-(2147483647+1) ..2147483647	ERROR¹	int	ERROR¹	int	int	int	long long	long long	long	long
0..4294967295	ERROR¹	unsigned int²	ERROR¹	unsigned int²	unsigned int²	unsigned int²	long long	long long	long	long
0..(2⁶³-1)	ERROR¹	long²	ERROR¹	long²	ERROR¹	long²	long long²	long long²	long²	long²
-2⁶³..(2⁶³-1)	ERROR¹	long²	ERROR¹	long²	ERROR¹	long²	long long²	long long²	long²	long²
0..2⁶⁴	ERROR¹	unsigned long²	ERROR¹	unsigned long²	ERROR¹	unsigned long²	unsigned long long²	unsigned long long²	unsigned long²	unsigned long²

	enum=int		enum=intlong				enum=small
	enum=int		32-bit compilation mode		64-bit compilation mode		32-bit compilation mode		64-bit compilation mode
Range	var	const	var	const	var	const	var	const	var	const
0..127	int	int	int	int	int	int	unsigned char	int	unsigned char	int
-128..127	int	int	int	int	int	int	signed char	int	signed char	int
0..255	int	int	int	int	int	int	unsigned char	int	unsigned char	int
0..32767	int	int	int	int	int	int	unsigned short	int	unsigned short	int
-32768..32767	int	int	int	int	int	int	short	int	short	int
0..65535	int	int	int	int	int	int	unsigned short	int	unsigned short	int
0..2147483647	int	int	int	int	int	int	unsigned int	unsigned int	unsigned int	unsigned int
-(2147483647+1) ..2147483647	int	int	int	int	int	int	int	int	int	int
0..4294967295	unsigned int¹	unsigned int²	unsigned int²	unsigned int²	unsigned int²	unsigned int²	unsigned int²	unsigned int²	unsigned int²	unsigned int²
0..(2⁶³-1)	ERR²	ERR²	long long²	long long²	long²	long²	unsigned long long²	unsigned long long²	unsigned long²	unsigned long²
-2⁶³..(2⁶³-1)	ERR²	ERR²	long long²	long long²	long²	long²	long long²	long long²	long²	long²
0..2⁶⁴	ERR²	ERR²	unsigned long long²	unsigned long long²	unsigned long²	unsigned long²	unsigned long long²	unsigned long long²	unsigned long²	unsigned long²

Notes:

These enumerations are too large for the -qenum=1|2|4|int setting. A Severe error is issued and compilation stops. To correct this condition, you should reduce the range of the enumerations, choose a larger -qenum setting, or choose a dynamic -qenum setting, such as small or intlong.
Enumeration types must not exceed the range of int when compiling C applications to ISO C 1989 and ISO C 1999 Standards. With the stdc89 | stdc99 language level in effect, the compiler will behave as follows if the value of an enumeration exceeds the range of int and the -qenum option in effect supports this value:
- If -qenum=int is in effect, a severe error message is issued and compilation stops.
- For all other settings of -qenum, an informational message is issued and compilation continues.

The #pragma enum directive must precede the declaration of enum variables that follow; any directives that occur within a declaration are ignored and diagnosed with a warning.

For each #pragma enum directive that you put in a source file, it is good practice to have a corresponding #pragma enum=reset before the end of that file. This should prevent one file from potentially changing the setting of another file that includes it.

Examples

If the following fragment is compiled with the enum=small option:

enum e_tag {a, b, c} e_var;

the range of enumeration constants is 0 through 2. This range falls within all of the ranges described in the table above. Based on priority, the compiler uses predefined type unsigned char.

If the following fragment is compiled with the enum=small option:

enum e_tag {a=-129, b, c} e_var;

the range of enumeration constants is -129 through -127. This range only falls within the ranges of short (signed short) and int (signed int). Because short (signed short) is smaller, it will be used to represent the enum.

The following code segment generates a warning and the second occurrence of the enum pragma is ignored:

#pragma enum=small
enum e_tag {
  a,
  b,
  #pragma enum=int /* error: cannot be within a declaration */ 
  c
} e_var;
#pragma enum=reset
#pragma enum=reset /* second reset isn't required */

Predefined macros

None.