c++编写一直报错应输入类型说明符

#include<iostream>
using namespace std;

class build;
class goodgay{
    public:
    goodgay();
    void checkbuild();
    build * b;
    
};
class build{
    public:
    friend void goodgay::checkbuild();
    build(); 
    public:
    int i;
    private:
    int j;
};

build::build()
{
    i=2;
    j=3;
}

goodgay::goodgay()
{
    b=new b;  **//就额是这个地方报错**
}

void goodgay::checkbuild()
{
    cout<<"i= "<<b->i<<endl;
    cout<<"j= "<<b->j<<endl;
}

int main()
{
    build b;
    goodgay g;
 
    g.checkbuild();
    system("pause");
    return 0;
}

new b这里有问题，没有class是b你应该是build吧

 b=new build;  //**//就额是这个地方报错**