Construction and destruction of objects when exceptions are thrown

[thamizh.veriyan]

I compiled this code on gcc 4.1.2 and the output I got seems to be a
bit weird.

Here is the code:

#include <iostream>

class A{
public:
A(){std::cout << "Constructor" << std::endl;}
~A(){std::cout << "Destructor" << std::endl;}
};

void display(){
A mystr;
throw mystr;
}

int main() {
try{
display();
}
catch(A str){
}
return 0;
}

The output happens to be:
Constructor
Destructor
Destructor
Destructor

I don't know if I am missing something. I checked all the references
that I have for exceptions. Looks like local objects get deleted
normally when exceptions are thrown. I cant seem to explain this
output. Would be grateful if the members here can help me with this.

Regards
Dana

 

[Victor Bazarov]

I compiled this code on gcc 4.1.2 and the output I got seems to be a
bit weird.

Here is the code:

#include <iostream>

class A{
public:
A(){std::cout << "Constructor" << std::endl;}
~A(){std::cout << "Destructor" << std::endl;}
};

void display(){
A mystr;
throw mystr;
}

int main() {
try{
display();
}
catch(A str){
}
return 0;
}

The output happens to be:
Constructor
Destructor
Destructor
Destructor

I don't know if I am missing something. I checked all the references
that I have for exceptions. Looks like local objects get deleted
normally when exceptions are thrown. I cant seem to explain this
output. Would be grateful if the members here can help me with this.

Your 'A' class has a copy constructor which you forgot to consider.

V

 

[John Harrison]

Your 'A' class has a copy constructor which you forgot to consider.

V

It's just incredible how many times we get this post.

john

 

[Piyo]

int main() {
try{
display();
}
catch(A str){

catch(A &str){ <-- catch using refs
On a related note, please make it a habit to catch by reference. It's
highly recommended (not required).

http://www.parashift.com/c++-faq-lite/exceptions.html#faq-17.7

 

[Victor Bazarov]

It's just incredible how many times we get this post.

If it's so frequently asked (which I can't vouch for), then perhaps
somebody <wink-wink> could write up an entry for Marshall Cline to
add to the FAQ Lite...

V