MSDN里的一段代码不能编译，是关于全局变量的

[max_xy]

// Library header file lib1.h
int libglobal;
int callappfunc(int * ptrlib);
void libfuncA(char * buffer);
int libfuncB(int const * mainint);
----------------------------------------------------------------------
// This is a header file of the library local functions-- lib2.h
int liblocalA(int x, int y);
----------------------------------------------------------------------
// This is the library source file lib1.c
#include <stdio.h>
#include "lib1.h"
#include "lib2.h"
libglobal = 20;
void libfuncA(char * buffer)
{
int i =0;
printf("Printing in Library \n%s\n\n", buffer);
printf("Value of i: %d\n", i);
}

int libfuncB(int const * mainint)
{
int returnvalue;
int localint;
int libvalue = 3;
localint = *mainint;
returnvalue = liblocalA(localint, libglobal);

libvalue = callappfunc(&libvalue);
printf("Print return value from app callback :%d\n", libvalue);
return returnvalue;

}
int liblocalA(int x, int y)
{
return (x + y);
}
----------------------------------------------------------------------
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上面这段代码，编译时候报告libglobal 缺少类型

[3jaja]

// Library header file lib1.h
extern int libglobal;
int callappfunc(int * ptrlib);
void libfuncA(char * buffer);
int libfuncB(int const * mainint);