constructor question

[junw2000]

I allocate memory in a constructor of my class. If the constructor
crashes, how to recollect the resource, i.e., deallocate memory?

Thanks.

Jack

 

[Kai-Uwe Bux]

I allocate memory in a constructor of my class. If the constructor
crashes, how to recollect the resource, i.e., deallocate memory?

A typical idiom is to use std::auto_ptr for that purpose:


#include <utility>
#include <iostream>

struct A {

int num;

A ( int n )
: num ( n )
{}

~A ( void ) {
std::cout << num << " destroyed properly.\n";
}

};

struct X {

A * a_ptr;
A * b_ptr;

X ( void ) {
std::auto_ptr< A > a_helper ( new A ( 1 ) );
std::auto_ptr< A > b_helper ( new A ( 2 ) );

throw 2;

a_ptr = a_helper.release();
b_ptr = b_helper.release();
}

};

int main ( void ) {
try {
X dummy;
}
catch ( ... ) {}
}



Best

Kai-Uwe Bux

 

[Daniel T.]

I allocate memory in a constructor of my class. If the constructor
crashes, how to recollect the resource, i.e., deallocate memory?

Crashes? If the constructor throws an exception, you are going to have
to catch it, deallocate your memory, and then re-throw the exception.