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LastKey
Find the last entry in an index file.
Short Name
LSTKEY()
Type
Low-Level index file function
Declaration
LONG LastKey(FILNO keyno, pVOID idxval)
Description
In V12 the file number typedef was formally changed from COUNT, a two-byte value to FILNO, a four-byte value. Refer to this link for compatibility details. Four Byte File Numbering
LastKey() searches index file keyno for the last entry in the index. If successful, it copies the last index entry into the space pointed to by idxval.
Return
LastKey() returns the data record position associated with the last entry in the index file. If the index is empty or an error is detected, LastKey() returns zero. If LastKey() returns zero, check uerr_cod to see if an error occurred: if uerr_cod is also zero, then the index is empty; otherwise, an error condition was detected. See c-tree Error Codes in the c-tree Programmer’s Reference Guide for a complete listing of valid c-tree error values.
Example
TEXT idxval[10];
FILNO keyno;
if (LastKey(keyno,idxval))
printf("\nLast index entry = %.10s", idxval);
else {
printf("\nEither index is empty or an error occurred.");
if (uerr_cod)
printf("\Error = %d",uerr_cod);
else
printf("\Index is empty.);
}
Limitations
No check is made to determine if idxval points to a region sufficiently large to accept a key value from the index file. If the area is too small, either code or data will be clobbered. Use GetCtFileInfo() to determine the key length.
The key value returned by this function will be a properly formatted key value (i.e., HIGH_LOW order, forced to upper case, etc.). The main issue is if binary key values will be displayed on a LOW_HIGH machine, it will be necessary to reverse any numeric segments. Key Segment Modes (Key Segment Modes, /doc/ctreeplus/30863.htm) in the c-tree Programmer’s Reference Guide contains suggestions for manipulating the key value.
The recbyt parameter in this function is a 4-byte value capable of addressing at most 4 gigabytes. If your application supports HUGE files (greater than 4 gigabytes), you must use the ctSETHGH() and ctGETHGH() functions to set or get the high-order 4 bytes of the file offset. See also Record Offsets Under Huge File Support.
See also
GetCtFileInfo(), FirstKey(), NextKey()
