求助：怎么编译通过不了？

// static data member
//=====================================
#include<iostream.h>
#include<string.h>
using namespace std;
//-------------------------------------
class Student
{
static int number;
string name;
public:
void set(string str)
{
name = str;
number++;
};
void print()
{ cout<<name<<" -> students are "<<number<<" numbers\n"; };
};
//-----------------------------------
//int Student::number = 0; //静态数据成员在类外分配空间和初始化
//-------------------------------------
void fn()
{
Student s1;
s1.set("Jenny");
Student s2;
s2.set("Randy");
s1.print();
}//------------------------------------
int main(){
Student s;
s.set("Smith");
fn();
s.print();
}//====================================