### AST_MAPKEY

Get the key at a given index within the KeyMap

#### Description:

This function returns a string holding the key for the entry with the given index within the KeyMap.

This function is intended primarily as a means of iterating round all the elements in a KeyMap. For this purpose, the number of entries in the KeyMap should first be found using AST_MAPSIZE and this function should then be called in a loop, with the index value going from one to the size of the KeyMap. The index associated with a given entry is determined by the SortBy attribute.

#### Invocation

RESULT = AST_MAPKEY( THIS, INDEX, STATUS )

#### Arguments

##### THIS = INTEGER (Given)
Pointer to the KeyMap.
##### INDEX = INTEGER (Given)
The index into the KeyMap. The first entry has index one, and the last has index SIZE, the value returned by the AST_MAPSIZE function.
##### STATUS = INTEGER (Given and Returned)
The global status.

The key value.

#### Notes:

• A blank string will be returned if this function is invoked with STATUS set to an error value, or if it should fail for any reason.