A try-catch problem in C++ - 未名空间MITBBS历史存档

国际科技财经博客移民网络热点娱乐民生时事公众号

Redian新闻

>未名空间

>Programming - 葵花宝典

A try-catch problem in C++

A try-catch problem in C++# Programming - 葵花宝典

g*n2005-08-19 07:08

1 楼

#include
using namespace std;
class A {
public:
A() {
cout << "A::A()" << endl;
}
~A() {
cout << "A::~A()" << endl; throw "A::exception";
}
};
class B {
public:
B() {
cout << "B::B()" << endl; throw "B::exception";
}
~B() {
cout << "B::~B()";
}
};
int main(int, char**) {
try {
cout << "Entering try...catch block" << endl;
A objectA;
B objectB;
cout << "Exiting try...catch block" << endl;
} catch (const char* ex) {
cout << ex << endl;
}
return 0;
}
output:
A::A();
B::B();
B::~B();
Abor

y*i2005-08-19 07:08

2 楼

When B() throw an exception, it will call destructor of ~A() to clean up.
However ~A() throw an exception again. There is only one catch. This kind of
problem belongs to the kind of exception happended in Constructor and
destructor. remove the exception in ~A().
Suggest, don't throw exception in constructir and destrcuor. If you have to,
catch it immediately.

【在 g*****n 的大作中提到】

: #include
: using namespace std;
: class A {
: public:
: A() {
: cout << "A::A()" << endl;
: }
: ~A() {
: cout << "A::~A()" << endl; throw "A::exception";
: }

t*t2005-08-19 07:08

3 楼

You are usually not supposed to throw exception in destructor.
If a dtor throw exception in the process of stack unrolling
(i.e. processing another exception), the program calls a pre-defined
function and exits immediately, there's no cure for this.
However, throwing exception in constructor is perfectly legal and will
often be met, e.g. if constructor calls new and new throws out bad_alloc.

【在 y****i 的大作中提到】

: When B() throw an exception, it will call destructor of ~A() to clean up.
: However ~A() throw an exception again. There is only one catch. This kind of
: problem belongs to the kind of exception happended in Constructor and
: destructor. remove the exception in ~A().
: Suggest, don't throw exception in constructir and destrcuor. If you have to,
: catch it immediately.

M*n2005-08-19 07:08

4 楼

right, never throw up anything in d'tor.

【在 t****t 的大作中提到】

: You are usually not supposed to throw exception in destructor.
: If a dtor throw exception in the process of stack unrolling
: (i.e. processing another exception), the program calls a pre-defined
: function and exits immediately, there's no cure for this.
: However, throwing exception in constructor is perfectly legal and will
: often be met, e.g. if constructor calls new and new throws out bad_alloc.

y*i2005-08-19 07:08

5 楼

Just find the good answer to this question:
/// Destructor should never throw excetions.
Why: If a destrutor gets invoked due to the stack-unwinding process
initialized by the throwing of another exception, and that destructor throws
an exception, terminate() is invoked, which calls abort()
// from C++ FAQ book

【在 y****i 的大作中提到】