Untitled

Valgrind not showing errors with array copy?

#include <algorithm>

#include <iostream>

using namespace std;

 

int main()

{

  int a[7] = {1, 2, 3, 4, 5, 6, 7};

  int b[7];

  copy(a, a+7, b);

  for (int i=0; i<8; ++i)

    cout << b[i] << endl;

}

       

(gdb) b 1

Breakpoint 1 at 0x100000a64: file stdcopy.cpp, line 1.

(gdb) r

Starting program: /Users/Babai/pastebin/a.out

Reading symbols for shared libraries ++......................... done

 

Breakpoint 1, main () at stdcopy.cpp:7

7     int a[7] = {1, 2, 3, 4, 5, 6, 7};

(gdb) n

9     copy(a, a+7, b);

(gdb) s

std::copy<int*, int*> (__first=0x7fff5fbffb8c, __last=0x7fff5fbffba8, __result=0x7fff5fbffb70) at stl_algobase.h:398

398        const bool __in = __is_normal_iterator<_InputIterator>::__value;

(gdb) bt

#0  std::copy<int*, int*> (__first=0x7fff5fbffb8c, __last=0x7fff5fbffba8, __result=0x7fff5fbffb70) at stl_algobase.h:398

#1  0x0000000100000acd in main () at stdcopy.cpp:9

(gdb) up

#1  main () at stdcopy.cpp:10

10    for (int i=0; i<8; ++i)

(gdb) p &a

$1 = (int (*)[7]) 0x7fff5fbffb8c

(gdb) p a + 7

$2 = (int *) 0x7fff5fbffba8

       

#include <algorithm>

#include <iostream>

#include <cstring>

 

int main()

{

  int* a = new int[7];

  int* b = new int[7];

  std::memset(a, 0, sizeof(int) * 7);

  std::memset(b, 0, sizeof(int) * 7);

 

  std::copy(a, a+7, b);

 

  for (int i=0; i<8; ++i)

    std::cout << b[i] << std::endl;

 

  delete[] a;

  delete[] b;

}

       

(gdb) down

#0  std::__copy_aux<int*, int*> (__first=0x7fff5fbffb8c, __last=0x7fff5fbffba8, __result=0x7fff5fbffb70) at stl_algobase.h:313

313                  && __are_same<_ValueTypeI, _ValueTypeO>::__value);

(gdb) n

315       return std::__copy<__simple, _Category>::copy(__first, __last, __result);

(gdb) s

std::__copy<true, std::random_access_iterator_tag>::copy<int> (__first=0x7fff5fbffb8c, __last=0x7fff5fbffba8, __result=0x7fff5fbffb70) at stl_algobase.h:298

298       std::memmove(__result, __first, sizeof(_Tp) * (__last - __first));

(gdb) list

293     {

294       template<typename _Tp>

295         static _Tp*

296         copy(const _Tp* __first, const _Tp* __last, _Tp* __result)

297         {

298       std::memmove(__result, __first, sizeof(_Tp) * (__last - __first));

299       return __result + (__last - __first);

300     }

301     };

302