Run the C preprocessor first
With Informix® ESQL/C, you change the default order of processing when you compile your Informix® ESQL/C program. Informix® ESQL/C allows you to run the C preprocessor on the Informix® ESQL/C source file first, and then pass that file to the Informix® ESQL/C preprocessor. This feature enables your Informix® ESQL/C program to access variables made available by C preprocessor directives.