6.2.1 stdinc.h

The macro package stdinc.h provides all basic definitions that ALL of NEMO's code must include as the first include file. It also replaces the often used stdio.h include file in C programs. The stdinc.h include file will provide us with a way to standardize on future expansions, and make code more machine/implementation independent (e.g. POSIX.1). In addition, it defines a more logical standard for C notation. For example, the normal C practice of using pointers to character for pointer to byte, or integer for bool, tends to encourage a degree of sloppy programming, which can be hard to understand at a later date.

A few of the basic definitions in this package:

$\bullet$ NULL:

macro for 0, used to distinguish null characters and null pointers. This is often already defined by stdio.h. There is potential trouble when NULL has been set to (void *)0, '\0' is OK though. Example on IBM's AIX operating system.

$\bullet$ bool:

typedef for short int or char, used to specify boolean data. See also next item. ^6.2.

$\bullet$ TRUE, FALSE:

macros for 1 and 0, respectively, following normal C conventions.

$\bullet$ byte:

typedef for unsigned char, used to specify byte-sized data.

$\bullet$ string:

typedef for char *, used to point to strings. Don't use string for pointers you increment, decrement or explicitly follow (using *); such pointers are really char *.

$\bullet$ real, realptr:

typedef for float or double (float * or double *, respectively), depending on the use of the SINGLEPREC flag. The default is double.

$\bullet$ proc, iproc, rproc:

typedefs for pointers to procedures (void functions), integer-valued functions and real-valued functions respectively.

$\bullet$ local, permanent:

macros for static. Use local when declaring variables or functions within a file to be local to that file. They will not appear in the symbol table be usable as external symbols. Use permanent within a function, to retain their value upon subsequent re-entries in that function.

$\bullet$ PI, TWO_PI, FOUR_PI, HALF_PI, FRTHRD_PI:

macros for $\pi$, $2\pi$, $4\pi$, $\pi/2$ and $4\pi/3$, respectively.

$\bullet$ ABS(x), SGN(x):

macros for absolute value and sign of x, irrespective of the type of x.. Beware of side effects.

$\bullet$ MAX(x,y), MIN(x,y):

macros for the maximum and minimum of x,y, irrespective of the type of x,y. Beware of side effects.

$\bullet$ stream:

typedef for FILE *. They are mostly used with the NEMO functions stropen and strclose, which are functionally similar to fopen(3) and fclose(3), plus some added NEMO quirks. (see section  below)