Convert BSTR to int

Question

Does any one know how can I convert a BSTR to an int in VC++ 2008

Thanks in advance.

Answer 1

You can pass a BSTR safely to any function expecting a wchar_t *. So you can use _wtoi().

Answer 2

Google suggests VarI4FromStr:

HRESULT VarI4FromStr(
  _In_   LPCOLESTR strIn,
  _In_   LCID lcid,
  _In_   ULONG dwFlags,
  _Out_  LONG *plOut
);

Answer 3

Try the _wtoi function:

int i = _wtoi( mybstr );

Answer 4

You should use ::VarI4FromStr(...).

Answer 5

BSTR s = SysAllocString(L"42");
int i = _wtoi(s);

Answer 6

You should be able to use boost::lexical_cast<>

#include <boost/lexical_cast.hpp>
#include <iostream>

int main()
{
    wchar_t     plop[]  = L"123";
    int value   = boost::lexical_cast<int>(plop);

    std::cout << value << std::endl;
}

The cool thing is that lexical_cast<>
It will work for any types that can be passed through a stream and its type safe!

Answer 7

This is a method I use to parse values out of strings. It's similar to Boost's lexical cast.

std::wistringstream iss(mybstr);   // Should convert from bstr to wchar_t* for the constructor
iss >> myint;                      // Puts the converted string value in to myint
if(iss.bad() || iss.fail())
{
   // conversion failed
}

Answer 8

You should use VarI4FromStr like others pointed out. BSTR is not wchar_t* because of differences in their NULL semantics (SysStringLen(NULL) is ok, but wcslen(NULL) is not).