Constants and Defined Types

This section lists the constants and types defined by the Support Kit and used throughout the entire Be operating system. Not included here are constants used as status_t values (error codes). They're listed in "Error Codes".

Constants

Boolean Constants

Declared in: be/support/SupportDefs.h

Constant	Value
false	0
true	1

These constants are defined as values for the bool type (described in the next section). The BeOS defines them for C code only. Because they match the boolean symbols that are part of the C++ language, they let you use the same bool type and true and false values when programming in both languages.

See also: bool

Byte Swapping Constants

Declared in: be/support/ByteOrder.h

Constant	Description
B_SWAP_HOST_TO_LENDIAN	Convert from host byte order to little endian
B_SWAP_HOST_TO_BENDIAN	Convert from host byte order to big endian
B_SWAP_LENDIAN_TO_HOST	Convert from little endian to host byte order
B_SWAP_BENDIAN_TO_HOST	Convert from big endian to host byte order
B_SWAP_ALWAYS	Always convert endianness

These constants define the action to be taken by the swap_data() general byte swapping function.

See also: swap_data()

Encoding Conversion Constants

Declared in: be/support/UTF8.h

Constant
B_ISO1_CONVERSION
B_ISO2_CONVERSION
B_ISO3_CONVERSION
B_ISO4_CONVERSION
B_ISO5_CONVERSION
B_ISO6_CONVERSION
B_ISO7_CONVERSION
B_ISO8_CONVERSION
B_ISO9_CONVERSION
B_ISO10_CONVERSION
B_MAC_ROMAN_CONVERSION
B_SJIS_CONVERSION
B_EUC_CONVERSION

These constants identify character encodings to the convert_to_utf8() and convert_from_utf8() functions, which convert text to and from the standard UTF8 character encoding assumed by the BeOS. The identify the source encoding for a conversion to UTF-8 and the destination encoding for a conversion from UTF-8.

See also: convert_to_utf8(), the BFont class in the Interface Kit

Empty String

Declared in: be/support/SupportDefs.h

	const char * B_EMPTY_STRING

This constant provides a global pointer to an empty string ("").

URL MIME Types

Declared in: be/support/TypeConstants.h

Constant	Meaning
B_URL_HTTP	An HTTP (HyperText Transport Protocol) link
B_URL_HTTPS	An HTTPS (HyperText Transport Protocol Secure) link
B_URL_FTP	AN FTP (File Transfer Protocol) link
B_URL_GOPHER	A Gopher link
B_URL_MAILTO	A mailto (email) link
B_URL_NEWS	A news (usenet) link
B_URL_NNTP	An NNTP (network time protocol) link
B_URL_TELNET	A telnet link
B_URL_RLOGIN	An rlogin link
B_URL_TN3270	A TN3270 link
B_URL_WAIS	A WAIS (Wide Area Information Services) link
B_URL_FILE	A local file link

These are MIME type strings for various URL types. An application can register itself as a handler for one of these types. Once that's done, clicking a link of that type in NetPositive will cause that application to be launched, with a B_ARGV_RECEIVED message with the full URL as the second argument.

NULL and NIL

Declared in: be/support/SupportDefs.h

Constant	Value
NIL	0
NULL	0

These constants represent "empty" values. They're synonyms that can be used interchangeably.

Type Codes

Declared in: be/support/TypeConstants.h

Constant	Meaning
B_CHAR_TYPE	A single character
B_INT8_TYPE	An 8-bit integer
B_INT16_TYPE	A 16-bit integer
B_INT32_TYPE	A 32-bit integer
B_INT64_TYPE	A 64-bit integer
B_UINT8_TYPE	An unsigned 8-bit integer
B_UINT16_TYPE	An unsigned 16-bit integer
B_UINT32_TYPE	An unsigned 32-bit integer
B_UINT64_TYPE	An unsigned 64-bit integer
B_FLOAT_TYPE	A float
B_DOUBLE_TYPE	A double
B_BOOL_TYPE	A boolean value (the bool type)
B_OFF_T_TYPE	An off_t value
B_SIZE_T_TYPE	A size_t value
B_SSIZE_T_TYPE	An ssize_t value
B_POINTER_TYPE	A pointer of some kind (including void *)
B_OBJECT_TYPE	An object pointer (such as BMessage *)
B_MESSAGE_TYPE	A BMessage object (not BMessage *)
B_MESSENGER_TYPE	A BMessenger object
B_POINT_TYPE	A BPoint object
B_RECT_TYPE	A BRect object
B_PATH_TYPE	A BPath object
B_REF_TYPE	An entry_ref structure
B_RGB_COLOR_TYPE	An rgb_color structure
B_PATTERN_TYPE	A pattern structure
B_STRING_TYPE	A null-terminated character string
B_MONOCHROME_1_BIT_TYPE	Raw data for a monochrome bitmap (1 bit/pixel)
B_GRAYSCALE_8_BIT_TYPE	Raw data for a grayscale bitmap (8 bits per pixel)
B_COLOR_8_BIT_TYPE	Raw bitmap data in the B_COLOR_8_BIT color space
B_RGB_32_BIT_TYPE	Raw bitmap data in the B_RGB_32_BIT color space
B_TIME_TYPE	64-bit microsecond time_t data
B_MEDIA_PARAMETER_TYPE	A Media Kit parameter.
B_MEDIA_PARAMETER_WEB_T YPE	A Media Kit parameter web.
B_MEDIA_PARAMETER_GROUP _TYPE	A Media Kit parameter group.
B_RAW_TYPE	Raw, untyped data—a stream of bytes
B_MIME_TYPE	The type is specified by a MIME string.
B_ANY_TYPE	The type can be any type.

These constants describe the types of data held by BMessage objects (the Application Kit) and as resources and file system attributes (the Storage Kit). B_ANY_TYPE refers to all types; it indicates that the exact type doesn't matter. B_MIME_TYPE indicates that the name of the data in the BMessage is a MIME string that specifies its true data type. The other constants refer only to a particular type. The type_code defined type marks where these constants are used in the API.

Applications can define their own type codes for data types not found on this list. All the codes the BeOS defines have values formed by concatenating four uppercase letters into a multicharacter constant. For example, B_MESSENGER_TYPE is 'MSNG' and B_SIZE_T_TYPE is 'SIZT'.

See also: type_code

Defined Types

bigtime_t

Declared in: be/support/SupportDefs.h

	typedef int64 bigtime_t

This type records the time in microseconds as a 64-bit integer. Typically, a bigtime_t variable measures the system time, the number of microseconds since 12:00:00 AM January 1, 1970, UTC (Coordinated Universal Time).

See also: system_time()

bool

Declared in: be/support/SupportDefs.h

	typedef unsigned char bool

The C++ language defines bool as its basic boolean type. The BeOS extends the definition to C code, so you can use the same type in both languages. The true and false constants (listed above) are defined as boolean values.

Function Pointers

Declared in: be/support/SupportDefs.h

	typedef int (* B_PFI )()       typedef long (* B_PFL )()       typedef void (* B_PFV )()

These types define pointers to functions that return int, long, and void values respectively.

instantiation_func

Declared in: be/support/Archivable.h

	typedef BArchivable *(*instantiation_func) (BMessage *)

This type is a pointer to a function that can instantiate an object from a BMessage archive and return a pointer to the new object. The Instantiate() member function of BArchivable is such a function.

See also: the BArchivable class, find_instantiation_func()

Integer Types

Declared in: be/support/SupportDefs.h

typedef unsigned char uchar typedef signed char int8       typedef unsigned char uint8       typedef volatile signed char vint8       typedef volatile unsigned char vuint8 typedef short int16       typedef unsigned short uint16       typedef volatile short vint16       typedef volatile unsigned short vuint16 typedef long int32       typedef unsigned long uint32       typedef volatile long vint32       typedef volatile unsigned long vuint32 typedef long long int64       typedef unsigned long long uint64       typedef volatile long long vint64       typedef volatile unsigned long long vuint64

These type names are defined as convenient shorthands for standard integers of various sizes. They're used in place of int, short, and long throughout the BeOS API.

The number at the end of the type name indicates the size of the integer. For example, a uint32 is an unsigned 32-bit value. The type is guaranteed to be defined to its stated size for all platforms (thus their exact definitions may vary from platform to platform).

Using these types will make the code you write more portable. They'll help avoid problems as the operating system and your application move to other platforms.

status_t

Declared in: be/support/SupportDefs.h

	typedef int32 status_t

This type indicates an error code; it's used mainly for function return values.

See also: "Error Codes"

type_code

Declared in: be/support/SupportDefs.h

	typedef uint32 type_code

This type is used for the integer codes that indicate a particular data type. The codes—such as B_UINT32_TYPE and B_MIME_TYPE—mark the type of data added to a message or stored as a resource and also appear in other contexts.

See also: "Type Codes", the BMessage class in the Application Kit, the BResource class in the Storage Kit