Question

I wrote a test C++ program to check the output of valgrind. The code is

#include <iostream>

void f() {
    int *pp = new int(1);
    std::cout << "pp is " << *pp << "\n";
}

int main() {
    f();
    return 0;
}

The valgrind command I used is

valgrind --leak-check=yes ./a.out

The output from Valgrind is

==2255== HEAP SUMMARY:
==2255==     in use at exit: 4 bytes in 1 blocks
==2255==   total heap usage: 1 allocs, 0 frees, 4 bytes allocated
==2255== 
==2255== 4 bytes in 1 blocks are definitely lost in loss record 1 of 1
==2255==    at 0x4C2B1C7: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==2255==    by 0x400786: f() (in /run/shm/a.out)
==2255==    by 0x4007CC: main (in /run/shm/a.out)
==2255== 
==2255== LEAK SUMMARY:
==2255==    definitely lost: 4 bytes in 1 blocks
==2255==    indirectly lost: 0 bytes in 0 blocks
==2255==      possibly lost: 0 bytes in 0 blocks
==2255==    still reachable: 0 bytes in 0 blocks
==2255==         suppressed: 0 bytes in 0 blocks

I am using a Ubuntu machine:
Linux Sun 3.2.0-27-generic #43-Ubuntu SMP Fri Jul 6 14:25:57 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

gcc version “4.6.3”

gcc parameter I used “-g -m64”

I think it should be eight bytes, right?

Answer 1

No, it shouldn’t be eight bytes unless sizeof(int)==8 on your platform.

You’re allocating, and leaking, a single int, not a pointer.