如何在C中转发类的声明？

发布时间：2020-12-16 09:43:43 所属栏目：百科来源：网络整理

导读：为什么A和B类的前向声明不起作用？ #include iostreamusing namespace std;class A,B; class A {public: A() { new B(); }};class B {public: B() { new A(); }};int main () { A a = new A(); B b = new B();}; 编译器错误： classes.cpp:4:8: error: expec

为什么A和B类的前向声明不起作用？

#include <iostream>
using namespace std;

class A,B;    

class A {
public:
    A() {
        new B();
    }
};

class B {
public:
    B() {
        new A();
    }
};

int main () {
    A a = new A();
    B b = new B();
};

编译器错误：

classes.cpp:4:8: error: expected unqualified-id before ‘,’ token
classes.cpp:4:10: error: aggregate ‘A B’ has incomplete type and cannot be defined
classes.cpp: In constructor ‘A::A()’:
classes.cpp:9:7: error: expected type-specifier before ‘B’
classes.cpp:9:7: error: expected ‘;’ before ‘B’
classes.cpp: In function ‘int main()’:
classes.cpp:22:14: error: conversion from ‘A*’ to non-scalar type ‘A’ requested
classes.cpp:23:4: error: expected ‘;’ before ‘b’

解决方法

像这样：

class A
{
public:
    A();
};

class B
{
public:
    B();
};

A::A() { new B(); }    // terrible code,leaks,serves no purpose
B::B() { new A(); }    // likewise

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!