Informix Error -666

-666 Variable variable-name must be declared INTEGER or SMALLINT.

In a FOR statement, loop variables that contain ranges must be declared to be INT or SMALLINT.

Example of error:

DEFINE var CHAR(10); FOR var IN (e1, e2 TO e3, e4) -- error ... END FOR;

Correction: Because the FOR statement contains a range operator (the TO clause), var must be declared as INT or SMALLINT.

Oninit® Troubleshooting Guidance

Reasons / Common Causes

-666 fires when a FOR statement's range-based loop variable (used with the TO clause) is declared as a type other than INTEGER/SMALLINT — per the official guidance, a ranged FOR loop variable specifically requires one of these two numeric types.

A loop variable declared CHAR, DECIMAL, or another non-integer type, per the official guidance's example contrast with CHAR — used in a FOR var = start TO end range loop.
A variable reused from elsewhere in the routine (declared for a different purpose, with a non-integer type) repurposed as a FOR loop's range variable without redeclaring it.

Solutions / Resolution

Declare the loop variable as INTEGER or SMALLINT, per the official guidance, before using it in a ranged FOR statement.
If the loop needs to iterate over non-integer values, iterate over an integer index instead and derive the non-integer value inside the loop body from that index.

Examples

The disallowed declaration

DEFINE i CHAR(2);
FOR i = 1 TO 10
  ...
END FOR;
-- -666: i must be INTEGER or SMALLINT for a ranged FOR

Corrected

DEFINE i INTEGER;
FOR i = 1 TO 10
  ...
END FOR;

Diagnostic Checks

Check the declared type of every FOR ... TO ... range loop's variable, confirming it's INTEGER/SMALLINT.

Related Errors / Related Topics

-660 — "Loop variable variable-name cannot be modified." A related FOR-loop restriction, about modifying the loop variable inside the loop rather than its declared type.

A ranged FOR loop's variable must be INTEGER/SMALLINT — redeclare it, or iterate over an integer index and derive any other value from it inside the loop.