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need help with destructor(im a noob)

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Join Date: Oct 2008

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atman

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need help with destructor(im a noob)

Feb 10th, 2009

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#include<stdio.h>
 
class q1 {
int id;
public:
 
q1() { id = 1; printf("mkdef: %d\n", id); }
q1(int start) { id = start + 1; 
				printf("mknew: %d\n", id); }
~q1() { printf("rm: %d\n", id); }
int something(int n) { printf("La-de-da:%d\n", id);
return n*(id+3);}
};
 
void foo(void)
{
	q1 one(1);
 
	one.something(4);
}
 
int main()
{
 
q1 a;
 
printf("%d\n", a.something(3));
foo();
q1 b(6);
printf("Bye..Bye...");
return 0;
}
#include<stdio.h>

class q1 {
int id;
public:

q1() { id = 1; printf("mkdef: %d\n", id); }
q1(int start) { id = start + 1; 
				printf("mknew: %d\n", id); }
~q1() { printf("rm: %d\n", id); }
int something(int n) { printf("La-de-da:%d\n", id);
return n*(id+3);}
};

void foo(void)
{
	q1 one(1);

	one.something(4);
}

int main()
{

q1 a;

printf("%d\n", a.something(3));
foo();
q1 b(6);
printf("Bye..Bye...");
return 0;
}

here is the output log:

mkdef: 1
La-de-da:1
12
mknew: 2
La-de-da:2
rm: 2
mknew: 7
Bye..Bye...rm: 7
rm: 1

Hello.,
im doing this walkthrough and i understand everything except the last part when the destructor gets called last, and rm=1., And at what point are we going out of scope? when we return 0, or with printf statement "bye bye"? when we created a new class q1 b(6), and passed 6 to the function q1(int start){id=start + 1;.....}, so isnt rm should be 7? why it 1 when i compile????? Greatly appreciated

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Join Date: Jul 2005

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Lerner

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Re: need help with destructor(im a noob)

Feb 11th, 2009

//create object called a
mkdef: 1
La-de-da:1
12
//create object called one
mknew: 2
La-de-da:2
//destroy object called two when closing } in foo() found
rm: 2
//create object called b
mknew: 7
Bye..Bye...
//find closing } for main() so destroy objects still in scope
//object b destroyed first since it is on top of stack of object variables, or at least that's how I understand it to work
rm: 7
//then destroy object a
rm: 1

I believe going out of scope occurs with closing brace creating the scope or with completion of loop if that's the definition of the scope.

Klatu Barada Nikto