Numerical types

C has a wide range of numerical types, of which the most useful are int, float and double. The ranges of the various types on the PWF system are given in the tables below. (Three types not shown are signed short, signed int and signed long, which are synonyms for short, int, and long respectively). To find out the ranges on other systems, use the code at the end of this section. On many systems, float quantities lack precision and double quantities are to be preferred. On the PWF all CCATSL functions require double floating-point quantities.

Table 1.1: The integer numerical types on the PWF system.

type name	size (bytes)	lower limit	upper limit
unsigned char	1	0	255
signed char	1	$-$128	127
char	1	$-$128	127
unsigned short	2	0	65535
short	2	$-$32768	32767
unsigned int	4	0	4294967295
int	4	$-$2147483648	2147483647
unsigned long	4	0	4294967295
long	4	$-$2147483648	2147483647

Table 1.2: The floating-point numerical types on the PWF system.

type name	size (bytes)	positive lower limit	positive upper limit	epsilon
float	4	1.175494e$-$38	3.402823e$+$38	1.192093e$-$07
double	8	2.225074e$-$308	1.797693e$+$308	2.220446e$-$16
long double	12	2.225074e$-$308	1.797693e$+$308	2.220446e$-$16