Wireshark · Wireshark-dev: [Wireshark-dev] how to include a head file

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I create a head file in wireshark,name peformance.h:

#include <glib.h>

typedef struct peformance_s

{

gfloat time[100];

      gfloat delay[100];

guint32 packetSize[100];

guint32 payload;

guint32 index;

guint32 temp_size;

gfloat temp_time;

}peformance;

extern peformance* peformance_test;

then I add the file to /gtk/main.c file ,

#include "peformance.h" //somebody told me not to use "../peformance.h" because there is subdir to search

peformance pef_test;

peformance *peformance_test=&pef_test;

in the ./wiretap/libpcap.c file, I want to use struct peformance ,

#include "peformance.h"  //or #include "../peformance.h",i do not know which one to use

peformance_test->index=0;

it shows to me one error,the error information is :

"   wiretap/.libs/libwiretap.so: undefined reference to `peformance_test'  "

what is going on and why is that?