What is glib?
glib is a C portability and utility library for UNIX-like systems and Windows. This chapter covers some of the most commonly-used library features in GTK+ and Gnome applications. glib is simple, and the concepts are familiar; so we’ll move quickly. For more complete coverage of glib, see glib.h or the free glib reference manual that comes with the library. (By the way: don’t be afraid of using the glib, GTK+, or Gnome header files; they are very clean and easy to read, and are handy as a quick reference. For that matter, don’t be afraid to look at the source code, if you have very specific questions about the implementation.)
glib’s various facilities are intended to have a consistent interface; the coding style is semi-object-oriented, and identifiers are prefixed with “g” to create a kind of names- pace.
glib has a single header file,
glib provides substitutes for many standard and commonly-used C language con- structs. This section describes glib’s fundamental type definitions, macros, memory allocation routines, and string utility functions.
Rather than using C’s standard types (int, long, etc.) glib defines its own. These serve a variety of purposes. For example, gint32 is guaranteed to be 32 bits wide, something no standard C type can ensure. guint is simply easier to type than unsigned. A few of the typedefs exist only for consistency; for example, gchar is always equivalent to the standard char.
The following primitive types are defined by glib:
• gint8, guint8, gint16, guint16, gint32, guint32, gint64, guint64—these give you in- tegers of a guaranteed size. Not all platforms provide 64-bit integers; if a platform has them, glib will define
G_HAVE_GINT64. (If it isn’t obvious, the guint types are unsigned, the gint types are signed.)
• gboolean is useful to make your code more readable, since C has no bool type.
• gchar, gshort, glong, gint, gfloat, gdouble are purely cosmetic.
• gpointer may be more convenient to type than void *. gconstpointer gives you const void*. (const gpointer will not do what you typically mean it to; spend some time with a good book on C if you don’t see why.)