All DB-Library/C applications require these header files:
sybfront.h – defines symbolic constants such as function return values, described in the Open Client DB-Library/C Reference Manual, and the exit values STDEXIT and ERREXIT. The sybfront.h file also includes type definitions for datatypes that can be used in program variable declaration.
sybdb.h – contains additional definitions and typedefs, most of which are meant to be used only by the DB-Library/C routines. Use the contents of sybdb.h only as documented in the Open Client DB-Library/C Reference Manual.
syberror.h – contains error severity values and should be included if the program refers to those values.
See the Open Client DB-Library/C Reference Manual