您可以实现类型转换运算符来实现这一点，例如

class A
{
int m_a;
public ：
A（ int a = 0 ）：m_a（a）{}
operator int （）{ return m_a;} // 类型转换操作符到'int'类型

};
int _tmain（ int argc，_TCHAR * argv []）
{
A obA;
int a = obA;
return 0 ;
}

how to make it work the line int a = obA; in the following code snippet.

class A
{
    int m_a;
public:
    int operator =(int a)
    {
        m_a = a;
        return 0;
    }

};
int _tmain(int argc, _TCHAR* argv[])
{
    A obA;
    int a = obA;
    return 0;
}

You might implement the typecast operator to make that work, e.g.

class A
{
    int m_a;
public:
    A(int a=0):m_a(a){}
    operator int(){ return m_a;} // typecast operator to 'int' type

};
int _tmain(int argc, _TCHAR* argv[])
{
    A obA;
    int a = obA;
    return 0;
}