added an example for get_all_keys

Author: degawa

example/hashmaps/CMakeLists.txt

@@ -8,6 +8,7 @@ ADD_EXAMPLE(hashmaps_fnv_1_hasher)
 ADD_EXAMPLE(hashmaps_free_key)
 ADD_EXAMPLE(hashmaps_free_other)
 ADD_EXAMPLE(hashmaps_get)
+ADD_EXAMPLE(hashmaps_get_all_keys)
 ADD_EXAMPLE(hashmaps_get_other_data)
 ADD_EXAMPLE(hashmaps_hasher_fun)
 ADD_EXAMPLE(hashmaps_init)

example/hashmaps/example_hashmaps_get_all_keys.f90

@@ -0,0 +1,53 @@
+program example_set_other_data
+  use stdlib_kinds, only: int32
+  use stdlib_hashmaps, only: chaining_hashmap_type
+  use stdlib_hashmap_wrappers, only: fnv_1_hasher, &
+                                     key_type, other_type, set
+  implicit none
+  type(chaining_hashmap_type) :: map
+  type(key_type)   :: key
+  type(other_type) :: other
+
+  type(key_type), allocatable :: keys(:)
+  integer(int32) :: i
+
+  call map%init(fnv_1_hasher)
+
+  ! adding key-value pairs to the map
+  call set(key, "initial key")
+  call set(other, "value 1")
+  call map%map_entry(key, other)
+
+  call set(key, "second key")
+  call set(other, "value 2")
+  call map%map_entry(key, other)
+
+  call set(key, "last key")
+  call set(other, "value 3")
+  call map%map_entry(key, other)
+
+  ! getting all the keys in the map
+  call map%get_all_keys(keys)
+
+  print '("Number of keys in the hashmap = ", I0)', size(keys)
+  !Number of keys in the hashmap = 3
+
+  do i = 1, size(keys)
+    print '("Value of key ", I0, " = ", A)', i, key_to_char(keys(i))
+  end do
+  !Value of key 1 = initial key
+  !Value of key 2 = second key
+  !Value of key 3 = last key
+
+contains
+  !Converts key type to character type
+  function key_to_char(key) result(str)
+    implicit none
+    type(key_type), intent(in) :: key
+    character(:), allocatable :: str
+    character(:), allocatable :: str_mold
+
+    allocate( character(len=size(key%value)) :: str_mold )
+    str = transfer(key%value, str_mold)
+  end function key_to_char
+end program example_set_other_data