V532. Consider inspecting the statement of '*pointer++' pattern. Probably meant: '(*pointer)++'

12.09.2011

The analyzer detected a potential error: a pointer dereferencing operation is present in code but the value the pointer refers to is not used in any way.

Let's study this sample:

int *p;
...
*p++;

The "*p++" expression performs the following actions. The "p" pointer is incremented by one, but before that a value of the "int" type is fetched from memory. This value is not used in any way, which is strange. It looks as if the dereferencing operation "*" is unnecessary. There are several ways of correcting the code:

1) We may remove the unnecessary dereferencing operation - the "*p++;" expression is equal to "p++;":

int *p;
...
p++;

2) If the developer intended to increment the value instead of the pointer, we should write it so:

int *p;
...
(*p)++;

If the "*p++" expression's result is used, the analyzer considers the code correct. This is a sample of safe code:

while(*src)
 *dest++ = *src++;

Let's study a sample taken from a real application:

STDMETHODIMP CCustomAutoComplete::Next(
  ULONG celt, LPOLESTR *rgelt, ULONG *pceltFetched)
{
  ...
  if (pceltFetched != NULL)
    *pceltFetched++;
  ...

In this case, parentheses are missing. This is the correct code:

if (pceltFetched != NULL)
    (*pceltFetched)++;

You can look at examples of errors from real projects which were detected by this diagnostic message.