win32com, BSTR, and null terminated strings

[Steve Holden]

Matt Helm wrote:
> 
> I am using win32com to access a third party COM interface but am
> having trouble using the string that is returned.
> 
> The vendor's docs show the following method:
>  
>     HRESULT CookString(BSTR param_a, short buf_size, [out, retval] BSTR* result_b);
> 
> param_a is a string to be processed.
> buf_size is the size of the returned string + 1.
> 
> I can't know what the exact length of the returned string will be but
> it is safe to assume it will not exceed 80 chars.
>  
> I have been calling it as such:
> 
>     import win32com.client
> 
>     o = win32com.client.Dispatch("BFG9000.BFG9000")
> 
>     r = o.Cook("ABCDEFG", 81)
> 
> 
> r comes back as a Python string 81 chars in length with a null at the
> end of the actual valid text. In other words, it is your normal buffer
> containing a null terminated string.
> 
> Python treats the whole 81 chars as valid - even though most of the
> string is garbage. This is the expected behavior and I understand
> this.
> 
> However, what is the proper way to recover the actual string? I have
> been using:
> 
>     r.split("\0", 1)[0]
> 
> but it seems like a bit of a kludge.
> 

It's perfectly good Python, though, so just forget about it or wrap it 
in a "cstring(s)" function do you don't have to look at it!

regards
  Steve
-- 
Steve Holden       +44 150 684 7255  +1 800 494 3119
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