D has built-in associative arrays also known as hash maps.
An associative array with a key type of
string and a value type
int is declared as follows:
The value can be accessed by its key and thus be set:
arr["key1"] = 10;
To test whether a key is located in the associative array, the
in expression can be used:
if ("key1" in arr) writeln("Yes");
in expression returns a pointer to the value if it
can be found or a
null pointer otherwise. Thus existence check
and writes can be conveniently combined:
if (auto val = "key1" in arr) *val = 20;
Access to a key which doesn't exist yields a
that immediately aborts the application. For safe access
with a default value,
get(key, defaultValue) can be used.
AA's have the
.length property like arrays and provide
.remove(key) member to remove entries by their key.
It is left as an exercise to the reader to explore