Declare function prototypes

Informix® ESQL/C provides the sqlproto.h header file to declare function prototypes for all Informix ESQL/C library functions. These function prototypes are required in the Informix ESQL/C source file that you compile with an ANSI C compiler. By default, the esql command processor does not include function-prototype declarations. Having the processor include the ANSI-compliant function prototypes for the Informix ESQL/C functions prevents an ANSI C compiler from generating warnings.

Restriction: Although you can use an ANSI C compiler, the Informix ESQL/C preprocessor does not fully support ANSI C, so you might not be able to preprocess all programs that follow the ANSI C standards.

Because the sqlproto.h file does not contain any Informix ESQL/C statements, you can include this file in either of the following ways:

With the Informix ESQL/C include preprocessor directive:
```
EXEC SQL include sqlproto;
```
With the C #include preprocessor directive:
```
#include "sqlproto.h";
```