Data Types and Sizes
D provides fundamental data types for integers and floating-point constants. Arithmetic may
only be performed on integers in D programs. Floating-point constants may be
used to initialize data structures, but floating-point arithmetic is not permitted in
D. D provides a 32-bit and 64-bit data model for use in
writing programs. The data model used when executing your program is the
native data model associated with the active operating system kernel. You can
determine the native data model for your system using isainfo -b.
The names of the integer types and their sizes in each of
the two data models are shown in the following table. Integers are
always represented in twos-complement form in the native byte-encoding order of your
system.
Table 2-2 D Integer Data Types
Type Name |
32–bit Size |
64–bit Size |
|---|
char |
1 byte |
1 byte |
short |
2 bytes |
2 bytes |
int |
4 bytes |
4 bytes |
long |
4 bytes |
8 bytes |
long long |
8
bytes |
8 bytes |
Integer types may be prefixed with the signed or unsigned qualifier. If
no sign qualifier is present, the type is assumed to be signed.
The D compiler also provides the type aliases listed in the following
table:
Table 2-3 D Integer Type Aliases
Type Name |
Description |
|---|
int8_t |
1 byte signed integer |
int16_t |
2 byte signed integer |
int32_t |
4 byte signed integer |
int64_t |
8 byte
signed integer |
intptr_t |
Signed integer of size equal to a pointer |
uint8_t |
1 byte unsigned integer |
uint16_t |
2
byte unsigned integer |
uint32_t |
4 byte unsigned integer |
uint64_t |
8 byte unsigned integer |
uintptr_t |
Unsigned integer of size
equal to a pointer |
These type aliases are equivalent to using the name of the corresponding
base type in the previous table and are appropriately defined for each
data model. For example, the type name uint8_t is an alias for
the type unsigned char. See Chapter 8, Type and Constant Definitions for information on how to define your
own type aliases for use in your D programs.
D provides floating-point types for compatibility with ANSI-C declarations and types. Floating-point
operators are not supported in D, but floating-point data objects can be
traced and formatted using the printf() function. The floating-point types listed in
the following table may be used:
Table 2-4 D Floating-Point Data Types
Type Name |
32–bit Size |
64–bit Size |
|---|
float |
4 bytes |
4 bytes |
double |
8 bytes |
8
bytes |
long double |
16 bytes |
16 bytes |
D also provides the special type string to represent ASCII strings. Strings
are discussed in more detail in Chapter 6, Strings.
