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Guest
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 Posted: Sat Nov 11, 2006 12:57 am Post subject: What's wrong with this snippet? |
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Hi, any body can tell me what's wrong with following code? Is there
memory leak occured?
class ABC
{
char *p;
public:
ABC()
{
p = (char*)malloc(50);
}
~ABC()
{
free(p);
}
};
void main()
{
ABC *pabc = new ABC;
ABC abc;
delete pabc;
}
--
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Joshua Lehrer
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| Posted: Sat Nov 11, 2006 4:04 am Post subject: Re: What's wrong with this snippet? |
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{ Quoting a little more context would have been helpful. -mod }
"What's wrong with it" and "is there a memory leak" are two different
questions.
You will get a lot of people telling you what is "wrong" with the code.
As for checking for a memory leak, no, there is no memory explicitly
allocated by this program that is not also explicitly released. The
constructor allocates 'p' and the destructor frees it. Your main
allocates one object on the heap and one on the stack, and it properly
deallocates the one on the heap.
As for what is wrong, I'm quite sure that others will list them for
you.
joshua lehrer
http://www.lehrerfamily.com/
--
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John L Fjellstad
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| Posted: Sat Nov 11, 2006 6:02 am Post subject: Re: What's wrong with this snippet? |
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guojing1982423 (AT) yahoo (DOT) com.cn writes:
| Quote: | Hi, any body can tell me what's wrong with following code? Is there
memory leak occured?
class ABC
{
char *p;
public:
ABC()
{
p = (char*)malloc(50);
}
~ABC()
{
free(p);
}
};
void main()
{
ABC *pabc = new ABC;
ABC abc;
delete pabc;
}
|
main returns an int like this
int main()
otherwise, i can't see anything particularly wrong with the code.
--
John L. Fjellstad
web: http://www.fjellstad.org/ Quis custodiet ipsos custodes
Replace YEAR with current four digit year
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Guest
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| Posted: Sat Nov 11, 2006 10:10 am Post subject: Re: What's wrong with this snippet? |
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guojing1982423 (AT) yahoo (DOT) com.cn wrote:
| Quote: | Hi, any body can tell me what's wrong with following code? Is there
memory leak occured?
class ABC
{
char *p;
public:
ABC()
{
p = (char*)malloc(50);
}
~ABC()
{
free(p);
}
};
void main()
{
ABC *pabc = new ABC;
ABC abc;
delete pabc;
}
|
Apart from usal stuff like operatr= .
I wont exactly call it a memory leak. may be FMR or FMW and stuff in
purify terms.
--
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Ivan Novick
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| Posted: Sun Nov 12, 2006 10:10 am Post subject: Re: What's wrong with this snippet? |
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| Quote: | Hi, any body can tell me what's wrong with following code? Is there
memory leak occured?
class ABC
{
char *p;
public:
ABC()
{
p = (char*)malloc(50);
}
~ABC()
{
free(p);
}};
|
If a compiler generated copy constructor or assignment operator is
called then you will not do the malloc, but you will still try to do
the free.
You can declare your own assignment operator and copy constructor to
make sure they leave an object in a consistent state.
--
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Jiang
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| Posted: Sun Nov 12, 2006 9:48 pm Post subject: Re: What's wrong with this snippet? |
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John L Fjellstad wrote:
| Quote: | guojing1982423 (AT) yahoo (DOT) com.cn writes:
|
[snip]
| Quote: |
main returns an int like this
int main()
otherwise, i can't see anything particularly wrong with the code.
|
Using malloc requires the standard include file, of course this is
maybe just a typo.
--
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amit
Guest
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| Posted: Wed Nov 15, 2006 6:07 am Post subject: Re: What's wrong with this snippet? |
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In the above program, nothing in main could call the copy construtor or
the assign operator. Surely we should write our own if we change the
program to make use of it.
~ amit
Ivan Novick wrote:
| Quote: | Hi, any body can tell me what's wrong with following code? Is there
memory leak occured?
class ABC
{
char *p;
public:
ABC()
{
p = (char*)malloc(50);
}
~ABC()
{
free(p);
}};
If a compiler generated copy constructor or assignment operator is
called then you will not do the malloc, but you will still try to do
the free.
You can declare your own assignment operator and copy constructor to
make sure they leave an object in a consistent state.
|
--
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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