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 .


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/ByteSwap.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


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 ("").


Declared in: be/support/SupportDefs.h

Constant Value

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_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_ASCII_TYPE Text in ASCII format
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_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


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()


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.


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.


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"


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

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Last modified November 10, 1998.