这个程序的异常在哪

这个程序的错误在哪？
#include<iostream.h>
#include<string.h>
class Reader
{
public:
Reader(char *name){strcpy(Reader::name,name);};
void show_reader(class Book book);
private:
char name[64];
};
class Book
{
public:
Book(char *title){strcpy(Book::title,title);};
void show_book(void){cout<<title;};
friend Reader::show_reader(Book book);
private:
char title[64];
};
void Reader::show_reader(class Book book)
{cout<<"Reader:"<<name<<' '<<"Book:"<<book.title;};
void main()
{
Reader reader("Kris Jamsa");
Book favorite_book("Compiler Internals");
reader.show_reader(favorite_book);
}

[解决办法]
加个void

C/C++ code

void friend Reader::show_reader(Book book);