警告:重载的虚函数"Base :: process"仅在类"derived"中被部分覆盖

Question

我低于警告.我的部分代码是:

class Base {
public:
    virtual void process(int x) {;};
    virtual void process(int a,float b) {;};
protected:
    int pd;
    float pb;
};

class derived: public Base{
public:
    void process(int a,float b);
}

void derived::process(int a,float b){
    pd=a;
    pb=b;
    ....
}

我收到以下警告:

 Warning: overloaded virtual function "Base::process" is only partially overridden in class "derived"

我以任何方式将进程作为虚函数,所以我期待这个警告不应该来......这背后的原因是什么？

Answer 1

警告的原因

Warning: overloaded virtual function "Base::process" is only partially overridden in class "derived"

是你没有覆盖所有签名,你已经完成了

virtual void process(int a,float b) {;}

但不是

virtual void process(int x) {;}

另外,当你不覆盖并且不使用using Base::process将函数带到范围时,静态调用derived::process(int)甚至都不会编译.这是因为Derived process(int)在这种情况下没有.所以

Derived *pd = new Derived();
pd->process(0);

和

Derived d;
d.process(0);

不会编译.

添加using声明将解决此问题,通过指向Derived*的指针和选择运算符d.process(int)进行静态调用以进行编译和虚拟调度(通过基指针或引用调用派生)进行编译,无需警告.

class Base {
public:
    virtual void process(int x) {qDebug() << "Base::p1 ";};
    virtual void process(int a,float b) {qDebug() << "Base::p2 ";}
protected:
    int pd;
    float pb;
};

class derived: public Base{
public:
    using Base::process;

    /* now you can override 0 functions, 1 of them, or both
    *  base version will be called for all process(s) 
    *  you haven't overloaded
    */
    void process(int x) {qDebug() << "Der::p1 ";}
    void process(int a,float b) {qDebug() << "Der::p2 ";}
};

现在:

int main(int argc, char *argv[])
{
    derived d;
    Base& bref = d;
    bref.process(1);    // Der::p1
    bref.process(1,2);  // Der::p2 
    return 0;
}

Answer 2

您仅覆盖了 的两个重载之一process。您错过了仅使用int.

class Base {
public:
    virtual void process(int x) {;}; // You do *not* override this in derived
    virtual void process(int a,float b) {;}; // You do override this
// ...
};

根据您的需要，您可以：

1. 只需覆盖;int中的重载即可。derived或者

2. 使int重载成为非虚拟的并让它调用虚拟int, float重载。

两个旁注： (a) 尽管大多数编译器都接受它，但;函数体后面的 a 在语法上是错误的。(b) 受保护的成员变量通常与公共变量一样不受欢迎；您应该使用受保护的 getter/setter 并将变量设为私有。