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C6219

warning C6219: Implicit cast between semantically different integer types: comparing HRESULT to 1 or TRUE. Consider using SUCCEEDED or FAILED macro instead

This warning indicates that an HRESULT is being compared with an explicit, non-HRESULT value of one (1). This is likely to lead to incorrect results because the typical success value of HRESULT (S_OK) is 0; comparing it to a Boolean type will implicitly convert it to false.

The following code generates this warning because the CoGetMalloc returns an HRESULT, which then is compared to TRUE:

#include <windows.h>

void f( )
{
  HRESULT hr;
  LPMALLOC pMalloc;
  hr = CoGetMalloc(1, &pMalloc);
  
  if (hr == TRUE)
  {
    // success code ...
  }
  else
  {
    // failure code   
  }
}

Most of the time, this warning is caused by the code mistakenly testing an HRESULT against a Boolean. It is generally best to use the SUCCEEDED or FAILED macros to test the value of an HRESULT. To correct this warning, use the following code:

#include <windows.h>

void f( )
{
  HRESULT hr;
  LPMALLOC pMalloc;
  hr = CoGetMalloc(1, &pMalloc);
  
  if (SUCCEEDED(hr))
  {
    // success code ...
  }
  else
  {
    // failure code   
  }
}

For this warning, the SCODE type is equivalent to HRESULT.

Note that the use of malloc and free (and related dynamic memory APIs) have many pitfalls in terms of memory leaks and exceptions. To avoid these kinds of leaks and exception problems altogether, use the mechanisms that are provided by the C++ Standard Template Library (STL). These include shared_ptr, unique_ptr, and vector. For more information, see Smart Pointers (Modern C++) and Standard C++ Library Reference.

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