c - Not sure why I am getting an undefine refence to gss_str_to_oid error -

i using gssapi in c first time. trying reconstruct example on oracle doc http://docs.oracle.com/cd/e19683-01/816-1331/sampleprogs-1/index.html. in .c file call gss_str_to_oid(&min_stat, &tok, oid); , undefined reference error. included #include "gssapi.h" @ top of .c file. in gssapi.h there function call

om_uint32 krb5_callconv gss_str_to_oid(     om_uint32 *,        /* minor_status */     gss_buffer_t,       /* oid_str */     gss_oid *);  

so doing wrong? thought if included #include "gssapi.h" give me access function in gssapi. both files in src folder. doing wrong. using eclipse , in makefile under targets says all: gss-api. including of code below.

main

#include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include <ctype.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <error.h> #include <sys/stat.h> #include <fcntl.h>  #include "gssapi.h" #include "gssapi_ext.h" #include "gss-misc.h"  /* global mech oid needed display status, , acquire cred */ file *display_file; gss_oid g_mechoid = gss_c_null_oid;   void usage() {      fprintf(stderr, "usage: gss-client [-port port] [-d]"                         " [-mech mechoid] host service msg\n");      exit(1); }  static void parse_oid(char *mechanism, gss_oid *oid) {     char        *mechstr = 0, *cp;     gss_buffer_desc tok;     om_uint32 maj_stat, min_stat;      if (isdigit(mechanism[0])) {         mechstr = malloc(strlen(mechanism)+5);         if (!mechstr) {             printf("couldn't allocate mechanism scratch!\n");             return;         }         sprintf(mechstr, "{ %s }", mechanism);         (cp = mechstr; *cp; cp++)             if (*cp == '.')                 *cp = ' ';         tok.value = mechstr;     } else         tok.value = mechanism;     tok.length = strlen(tok.value);       maj_stat = gss_str_to_oid(&min_stat, &tok, oid);     if (maj_stat != gss_s_complete) {  //       display_status("str_to_oid", maj_stat, min_stat);         return;     }     if (mechstr)         free(mechstr); }  int main(argc, argv)      int argc;      char **argv; {     /* char *service_name, *hostname, *msg; */      char *msg;      char service_name[128];      char hostname[128];      char *mechanism = 0;      u_short port = 4444;      int use_file = 0;      om_uint32 deleg_flag = 0, min_stat;       display_file = stdout;       /* parse arguments. */       argc--; argv++;      while (argc) {           if (strcmp(*argv, "-port") == 0) {                argc--; argv++;                if (!argc) usage();                port = atoi(*argv);            } else if (strcmp(*argv, "-mech") == 0) {                argc--; argv++;                if (!argc) usage();                mechanism = *argv;            } else if (strcmp(*argv, "-d") == 0) {                deleg_flag = gss_c_deleg_flag;           } else if (strcmp(*argv, "-f") == 0) {                use_file = 1;           } else                 break;           argc--; argv++;      }      if (argc != 3)           usage();       if (argc > 1) {                 strcpy(hostname, argv[0]);         } else if (gethostname(hostname, sizeof(hostname)) == -1) {                         perror("gethostname");                         exit(1);         }        if (argc > 2) {         strcpy(service_name, argv[1]);         strcat(service_name, "@");         strcat(service_name, hostname);       }        msg = argv[2];       if (mechanism)          parse_oid(mechanism, &g_mechoid);  /*     if (call_server(hostname, port, g_mechoid, service_name,                    deleg_flag, msg, use_file) < 0)           exit(1);*/  /*      if (g_mechoid != gss_c_null_oid)          (void) gss_release_oid(&min_stat, &gmechoid); */       return 0; } 

gssapi.h

/* new v2 */ om_uint32 krb5_callconv gss_str_to_oid(     om_uint32 *,        /* minor_status */     gss_buffer_t,       /* oid_str */     gss_oid *);   

you can't include header have link library either dynamically or statically. there dll, lib, so, etc need add project? without makefile or project setup been shown in question; think not receive clear answer. including header file isn't enough, undefined not compilation error linker error, means missing reference because not linking library program.