疯狂报错，大神帮帮

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c++新手，下面这段代码疯狂报错

[C++] 纯文本查看 复制代码

#include<iostream>
using namespace std;
class test
{
    private:
    
        int math;
        int chinese;
        int english;
        float chemistry;
    
    public:
    
        void get((float) sub);
        ~test();
        test();
    
}
test::test()
{
    math=140;
    chinese=120;
    english=130;
    chemistry=40;
}
test::~test()
{
    cout<<"Get over!";
}
void test::get((float)sub)
{
    cout<<sub;
}
int main()
{
    {
        char*a;
        cout<<"Key the subject you want to know\n";
        cin>>a;
        cout<<"I know you want to know the grade of English\n";
        get(english);
    }
    return 0;
}