c – 异常处理中的混淆

概述考虑以下程序 #include <iostream>#include<cstdlib>using namespace std;class E { public: const char* error; E(const char* arg) : error(arg) { }};void my_terminate() { cout << "Call to 考虑以下程序

#include <iostream>#include<cstdlib>using namespace std;class E {   public:      const char* error;      E(const char* arg) : error(arg) { }};voID my_terminate() {  cout << "Call to my_terminate" << endl;}struct A {  A() { cout << "In constructor of A" << endl; }  ~A(){    cout << "In destructor of A" << endl;    throw E("Exception thrown in ~A()");  }};struct B {  B() { cout << "In constructor of B" << endl; }  ~B() { cout << "In destructor of B" << endl; }};int main() {  set_terminate(my_terminate);  try {    cout << "In try block" << endl;    A a;    B b;    throw E("Exception thrown in try block of main()"); // line 36  }  catch (E& e) {    cout << "Exception: " << e.error << endl;  }  catch (...) {    cout << "Some exception caught in main()" << endl;  }  cout << "Resume execution of main()" << endl;}

输出：

In try blockIn constructor of AIn constructor of BIn destructor of BIn destructor of ACall to my_terminatedisallowed system call: SYS_kill

在第36行中,从main中的try块抛出异常.现在为什么这个异常没有被处理程序捕获？

相反,“堆栈展开”过程继续.A的析构函数也抛出一个异常,它再次没有被任何处理程序捕获,而是调用my_terminate,为什么？

为什么在这两种情况下不调用处理程序？

解决方法 The C++ rule is that you must never throw an exception from a destructor that is being called during the “stack unwinding” process of another exception.

你在A的析构函数中抛出异常,这是你不应该做的事情.

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