\head.h(29) : error C2059: 语法错误 : "{"

#ifndef Rational_H_ // <-- 能跟类名
#define Rational_H_ // <-- 能跟类名
class Rational
{
public:
Rational();
Rational(int, int); //行错
private:
int m_zi;
int m_mu;
}; // <-