HP UX Fortran Software manual Unsigned integers, Logicals

Table 33 Size differences between HP Fortran and C data types

HP Fortran data types		C data types
	32-bit mode	64-bit mode	Sizes (in bits)
INTEGER	intor long	int	32
INTEGER*4	intor long	int	32
INTEGER*8	longlong	longor long long	64
REAL	float	float	32
DOUBLE PRECISION	double	double	64
REAL*16	long double	long double	128

Table 34 Size differences after compiling with +autodbl

HP Fortran data types		C data types
	32-bit mode	64-bit mode	Sizes (in bits)
INTEGER	longor long	long	64
INTEGER*4	intor long	int	32
INTEGER*8	longlong	long	64
REAL	float	float	64
DOUBLE PRECISION	long double	long double	128
REAL*16	long double	long double	128

The following sections provide more detailed information about language differences for the following data types:

•Unsigned integers

•Logicals

•Complex numbers

•Derived types

Unsigned integers

Unlike Fortran, C allows integer data types (char,int,short, and long) to be declared as either signed or unsigned. If a Fortran program passes a signed integer to a C function that expects an unsigned integer argument, C will interpret the bit pattern as an unsigned value.

An unsigned integer in C can represent twice the number of positive values as the same-sized integer in HP Fortran. If an HP Fortran program calls a C function that returns an unsigned integer and the return value is greater than can be represented in a signed integer, HP Fortran will interpret the bit pattern as a negative number.

Logicals

C uses integers for logical types. In HP Fortran, a 2-byte LOGICALis equivalent to a C short, and a 4-byte LOGICALis equivalent to a long or int. In C and HP Fortran, zero is false and any nonzero value is true. HP Fortran sets the value 1for true.

Data types 111