Maps are sorted dictionaries mapping keys to values. Currently they have limited functionality and few instantiations: maps of ints to ints and of strings to strings.

Basic functionality

All map types support the following basic operations.

Construction and destruction

Like other wrapped C++ classes in Flibcpp, maps are constructed using an interface function. The default constructor is an empty map. Maps are destroyed using the release type-bound subroutine.


The contents of the map can be changed with the following methods:

Add a new key-value pair to the map. If the key already exists, the value in the map will remain unchanged. An optional logical parameter can be passed that will be set to .true. if insertion was successful and .false. if the key already existed.
Assign the given value to the key, regardless of whether the value already existed.
Return the value for the specified key, creating it with a default value (zero for numeric types, empty for string types) if it does not exist.
Remove all items from the map.

The size method returns the number of elements, and count will return the number of elements with the given key.

Here’s an example of creating, modifying, and destroying a map:

use flc_map, only : Map => MapIntInt
type(Map) :: m
logical :: inserted = .false.
integer(C_INT) :: value
m = Map()
call m%insert(123, 456)
call m%insert(123, 567, inserted) ! inserted = false, value unchanged
call m%set(123, 567) ! value is changed
value = m%get(911) ! implicitly created value of zero
call m%erase(911)
call m%release()


Iterating over a map to determine its contents is not yet supported.