C++头文件声明cpp定义失败

Question

问题遇到的现象和发生背景

C++新手，目的是想写一个头文件声明类方法，然后用一个cpp来定义类方法，最后再写一个main.cpp来调用类方法，可是终端却显示 “undefined reference to ”类方法，

问题相关代码，请勿粘贴截图

#ifndef COMPLEX_H_     //头文件
#define COMPLEX_H_

class fushu{
    public:
    fushu(double x1,double x2);

    fushu operator + (const fushu&) const;

    fushu operator - (const fushu&) const ;

    fushu operator * (const fushu&) const;

    friend fushu operator * (double,const fushu&);

    fushu operator ~ () const;


    private:
    double a,b;

    friend ostream& operator <<(ostream& os ,fushu& mod){
    return os << "(" << mod.a << "," << mod.b << ")"<<endl;
    }
    friend std::istream& operator >>(istream&,fushu&);


};
#endif

#include <iostream>         //用来定义类方法的cpp
using namespace std;
#include "complex0.h"

fushu::fushu(double x1=0,double x2=0):a(x1),b(x2){}
fushu fushu::operator * (const fushu& mod) const  {
    fushu x;
    x.a=a*mod.a-b*mod.b;
    x.b=a*mod.b+b*mod.a;
    return x;
}
fushu fushu::operator + (const fushu& mod ) const {
    fushu x;
    x.a=a+mod.a;
    x.b=b+mod.b;
    return x;
}
fushu fushu::operator - (const fushu& mod) const {
    fushu x;
    x.a=a-mod.a;
    x.b=b-mod.b;
    return x;
}
fushu fushu::operator ~ ()const {
    fushu x;
    x.a=a;
    x.b=-b;
    return x;
}
fushu operator * (double x1,const fushu& mod) {
    fushu x;
    x.a=x1*mod.a;
    x.b=x1*mod.b;
    return x;
}
istream& operator >>(istream & is,fushu& mod){
}

#include <iostream>     //main.cpp
using namespace std;
#include "complex0.h"

int main(){
    fushu x1(2,3);   //调试构造函数
    cout << x1;        //调试重载符
     
}

运行结果及报错内容

c:/mingw/bin/../lib/gcc/mingw32/9.2.0/../../../../mingw32/bin/ld.exe: C:\Users\AppData\Local\Temp\cc9Ao64C.o:main.cpp:(.text+0x2f): undefined reference to `fushu::fushu(double, double)'
collect2.exe: error: ld returned 1 exit status

我的解答思路和尝试过的方法

尝试过把类方法的定义放到头文件里，然后就成功运行了

我想要达到的结果

所以实现头文件声明cpp定义的正确方法是什么呢，希望不吝赐教

Answer 1

你用的什么编译器呢。
需要把2个cpp文件都编译
g++ main.cpp fushu.cpp -o main.exe