I think this should be a memory leakage. Anyone agree?

[Zongjun Qi]

#include <iostream>
using namespace std;

class String{
public:
char *Str;
String(){
Str = new char[10000000];
}

~String(){
delete Str;
}
};

int main(){
String my1;
for(int i=0; i< 100000; i++){
String my2;
my2 = my1;
}
return 0;
}
-------------------------
Because inside the constructor, a new memory is allocated each time a
new object is created. And inside the for loop, my2.Str is repointed to
my1.Str, and thus the memory orginally allocated for my2 will be
"lost".

And if we run on Linux, the host should be expected to memory drained
to dry. But it didn't on my box. Wonder why...

[Victor Bazarov]

Zongjun Qi wrote:

#include <iostream>
using namespace std;

class String{
public:
char *Str;
String(){
Str = new char[10000000];
}

~String(){
delete Str;

Undefined behaviour. If the pointer is allocated using 'new[]', it
has to be disposed of using 'delete[]'.

}
};

int main(){
String my1;
for(int i=0; i< 100000; i++){
String my2;
my2 = my1;
}
return 0;
}
-------------------------
Because inside the constructor, a new memory is allocated each time a
new object is created. And inside the for loop, my2.Str is repointed
to my1.Str, and thus the memory orginally allocated for my2 will be
"lost".

Not only that, but 'my2' is destructed at the end of every loop, which
makes the memory allocated in 'my2' to be deleted more than once. Even
if you replace 'delete Str' with 'delete[] Str', the behaviour is going
to be undefined due to multiple deletion of the same pointer.

And if we run on Linux, the host should be expected to memory drained
to dry. But it didn't on my box. Wonder why...

Because the program has undefined behaviour, that's why.

V
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