BASICBASIC statementsnxtkey statement

nxtkey statement

The nxtkey statement scans forward through a key file along a key path.

Syntax

NXTKEY result FROM filevar,a.code,key,n THEN/ELSE

Parameter(s)

result Returned variable containing the keys retrieved in a multi-attribute dynamic array.
filevar Variable to which the data file has been opened.
a.code String expression containing the a (algebraic) processing code located in the file-defining item that identifies the index to use.

The index must have previously been created with create-index.
key Beginning key value at which to begin the retrieval.
n Number of keys to retrieve.

Description

This statement retrieves at most n keys. Fewer may be retrieved if end-of-file is reached.

Repetitive use of this statement is allowed with the last key from the previous statement being supplied as the beginning key for the next statement.

The ELSE clause is executed if the file is not a keyed file or if the specified a.code variable is invalid. If the ELSE clause executes, then SYSTEM(0) returns the error condition as:
0 The file was not a keyed file.
1 The a.code variable was invalid.

See also

Cruising and zooming commands, key statement, prvkey statement, root statement, then/else statement blocks, verify-index command

Parent topic: BASIC statements