This is lib/get_num.h (Listing 3-5, page 59), an example from the book, The Linux Programming Interface.
The source code file is copyright 2023, Michael Kerrisk, and is licensed under the GNU Lesser General Public License, version 3.
This page shows the "distribution" or "book" version of the file (why are there two versions?), or the differences between the two versions. You can switch between the views using the tabs below.
In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.
+/* get_num.h + + Header file for get_num.c. +*/ #ifndef GET_NUM_H #define GET_NUM_H #define GN_NONNEG 01 /* Value must be >= 0 */ #define GN_GT_0 02 /* Value must be > 0 */ /* By default, integers are decimal */ #define GN_ANY_BASE 0100 /* Can use any base - like strtol(3) */ #define GN_BASE_8 0200 /* Value is expressed in octal */ #define GN_BASE_16 0400 /* Value is expressed in hexadecimal */ long getLong(const char *arg, int flags, const char *name); int getInt(const char *arg, int flags, const char *name); #endif
Note that, in most cases, the programs rendered in these web pages are not free standing: you'll typically also need a few other source files (mostly in the lib/ subdirectory) as well. Generally, it's easier to just download the entire source tarball and build the programs with make(1). By hovering your mouse over the various hyperlinked include files and function calls above, you can see which other source files this file depends on.