The typedef
keyword is used to declare an
identifier as an alias for an existing type. Like all D type
declarations, typedef
is used outside of
probe clauses in a declaration of the following form:
typedefexisting-type
new-type
;
where existing-type
is any type
declaration and new-type
is an
identifier to be used as the alias for this type. For example,
the D compiler uses the following declaration internally to
create the uint8_t
type alias:
typedef unsigned char uint8_t;
You can use type aliases anywhere that a normal type can be
used, such as the type of a variable or associative array value
or tuple member. You can also combine typedef
with more elaborate declarations such as the definition of a new
struct
, as shown in the following example:
typedef struct foo { int x; int y; } foo_t;
In the previous example, struct foo
is
defined using the same type as its alias,
foo_t
. Linux C system headers often use the
suffix _t
to denote a
typedef
alias.