Check for missing indicator variables

If you include the -icheck option, the Informix® ESQL/C preprocessor generates code in your program that returns a runtime error if an SQL statement returns a null value to a host variable that does not have an associated indicator variable. For example, the following command tells the preprocessor to insert code that checks for null values into the demo1.ec program:
esql -icheck demo1.ec

If you do not use the -icheck option, Informix ESQL/C does not generate an error if the database server passes a null value to a host variable without an indicator variable.