求大神帮忙看下重载

代码如下：就是不能重载，别的没问题
#include <iostream>
#include <string>
using namespace std;
class student
{
int number;
string name;
public:
void setnum(int num)
{
number=num;
}
int getnum()
{
return number;
}
void student::printinfo()
{
cout<<student::getnum()<<endl;
}
void set_student(int num);
void set_student(int num,string n)
{
number=num;
name=n;
cout<<""<<number<<" "<<"姓名"<<name<<endl;
}
};
int main()
{
student stu;
stu.set_student(10,"李四");
stu.setnum(10);
stu.printinfo();
system("pause");
return 0;
}