#include "btree.h"

The bprvky function returns the previous key from the current root in the file associated with the btact context pointer. The key, a character string, is returned via the pointer in key. The value associated with the key will be returned in the integer location identified by value. value is declared as a BTint, which is normally a typedef for int, but with Large File Support will be a typedef for long long.

bprvky returns zero to indicate the previous key has been located. If no previous key exists, bnxtky returns the error code QNOKEY.

To initialise the B Tree position, a call to bfndky or btpos must be made before the first call to bprvky. Thereafter, repeated calls to bprvky may be made. Calls to bnxtky may be freely intermingled with calls to bprvky.

bprvky is prohibited when an index file is opened in shared mode and the current root supports duplicate keys. To use bprvky in this case, exclusive access to the index file must be gained via the btlock function.

A non-zero return from bprvky indicates an error occurred during the key location process.