'bad_cast' in namespace 'std' does not name a type 错误

Question

给定下一个代码：

#include <iostream>
using std::cout;
using std::endl;
using std::cerr;

class A {
public:
    virtual ~A() {
    }
};

class B: public A {
public:

};

int main() {
    int n = 4;
    A a;
    A& base = a;
    B* ptr = dynamic_cast<B*>(&base);
    if (ptr == NULL) {
        cerr << "base is not a B";
    }
    try {
        B& derived = dynamic_cast<B&>(base);
        derived = *ptr;
    } catch (std::bad_cast&) { // ERROR
        cerr << "base is not a B";
    }
    if (n == 3) {
    }
    return 0;
}

我收到此消息错误，我不明白是什么原因，我该如何解决？

'bad_cast' in namespace 'std' does not name a type

Answer 1

如果您在 http://en.cppreference.com/w/cpp/types/bad_cast 查找文档，它会在顶部告诉您每个 class/function 都需要包含哪些内容。在这种情况下，您需要包括 <typeinfo>

'bad_cast' in namespace 'std' does not name a type 错误

'bad_cast' in namespace 'std' does not name a type Error

c++

dynamic-cast

std