Practical C Programming, 3rd Edition

Appendix B. Ranges and Parameter Passing Conversions

Ranges

Table B-1 and Table B-2 list the ranges of various variable types.

Table B-1. 32-Bit UNIX Machine

Name	Bits	Low value	High value	Accuracy
int	32	-2147483648	2147483647
short int	16	-32768	32767
long int	32	-2147483648	2147483647
unsigned int	32	0	4294967295
unsigned short int	16	0	65535
unsigned long int	32	0	4294967295
char	8	System Dependent
unsigned char	8	0	255
float	32	-3.4E+38	3.4E+38	6 digits
double	64	-1.7E+308	1.7E+308	15 digits
long double	64	-1.7E+308	1.7E+308	15 digits

Table B-2. Turbo C++, Borland C++, and Most Other 16-bit Systems

Name	Bits	Low value	High value	Accuracy
int	16	-32768	32767
short int	16	-32768	32767
long int	32	-2147483648	2147483647
unsigned int	16	0	65535
unsigned short int	16	0	65535
unsigned long int	32	0	4294967295
char	8	-128	127
unsigned char	8	0	255
float	32	-3.4E+38	3.4E+38	6 digits
double	64	-1.7E+308	1.7E+308	15 digits
long double	80	-3.4E+4932	3.4E+4932	17 digits

Automatic Type Conversions to Use When Passing Parameters

In order to eliminate some of the problems that may occur when passing parameters to a function, C performs the following automatic conversions to function arguments as shown in Table B-3.

Table B-3. Automatic Conversions

Type	Converted to
char	int
short int	int
int	int
long int	long int
float	double
double	double
long double	long double
array	pointer