G_IS_DIR_SEPARATOR()

#define G_IS_DIR_SEPARATOR(c) ((c) == G_DIR_SEPARATOR || (c) == '/')

Checks whether a character is a directory separator. It returns TRUE for '/' on UNIX machines and for '\' or '/' under Windows.

Since 2.6

NULL

#  define NULL        (0L)

Defines the standard NULL pointer.

MIN()

#define MIN(a, b)  (((a) < (b)) ? (a) : (b))

Calculates the minimum of a and b .

MAX()

#define MAX(a, b)  (((a) > (b)) ? (a) : (b))

Calculates the maximum of a and b .

ABS()

#define ABS(a)	   (((a) < 0) ? -(a) : (a))

Calculates the absolute value of a . The absolute value is simply the number with any negative sign taken away.

For example,

CLAMP()

#define CLAMP(x, low, high)  (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))

Ensures that x is between the limits set by low and high . If low is greater than high the result is undefined.

For example,

G_STRUCT_MEMBER()

#define             G_STRUCT_MEMBER(member_type, struct_p, struct_offset)

Returns a member of a structure at a given offset, using the given type.

G_STRUCT_MEMBER_P()

#define             G_STRUCT_MEMBER_P(struct_p, struct_offset)

Returns an untyped pointer to a given offset of a struct.

G_STRUCT_OFFSET()

#define             G_STRUCT_OFFSET(struct_type, member)

Returns the offset, in bytes, of a member of a struct.

G_N_ELEMENTS()

#define G_N_ELEMENTS(arr)		(sizeof (arr) / sizeof ((arr)[0]))

Determines the number of elements in an array. The array must be declared so the compiler knows its size at compile-time; this macro will not work on an array allocated on the heap, only static arrays or arrays on the stack.

G_OS_WIN32

#define G_OS_WIN32

This macro is defined only on Windows. So you can bracket Windows-specific code in "#ifdef G_OS_WIN32".

G_OS_UNIX

#define G_OS_UNIX

This macro is defined only on UNIX. So you can bracket UNIX-specific code in "#ifdef G_OS_UNIX".

G_DIR_SEPARATOR

#define G_DIR_SEPARATOR '\\'

The directory separator character. This is '/' on UNIX machines and '\' under Windows.

G_DIR_SEPARATOR_S

#define G_DIR_SEPARATOR_S "\\"

The directory separator as a string. This is "/" on UNIX machines and "\" under Windows.

G_SEARCHPATH_SEPARATOR

#define G_SEARCHPATH_SEPARATOR ';'

The search path separator character. This is ':' on UNIX machines and ';' under Windows.

G_SEARCHPATH_SEPARATOR_S

#define G_SEARCHPATH_SEPARATOR_S ";"

The search path separator as a string. This is ":" on UNIX machines and ";" under Windows.

TRUE

#define TRUE (!FALSE)

Defines the TRUE value for the gboolean type.

FALSE

#define FALSE (0)

Defines the FALSE value for the gboolean type.

G_MEM_ALIGN

#  define G_MEM_ALIGN GLIB_SIZEOF_VOID_P

Indicates the number of bytes to which memory will be aligned on the current platform.

G_CONST_RETURN

#define G_CONST_RETURN

If G_DISABLE_CONST_RETURNS is defined, this macro expands to nothing. By default, the macro expands to const. The macro can be used in place of const for functions that return a value that should not be modified. The purpose of this macro is to allow us to turn on const for returned constant strings by default, while allowing programmers who find that annoying to turn it off. This macro should only be used for return values and for "out" parameters, it doesn't make sense for "in" parameters.