[in, out] variables - best not to reuse them! [moved]

[Haroon Sarwar]

spent a while wondering why szProp2 was returning a truncated string...D'oh! :-O TCHAR szProp1[256]; TCHAR szProp2[256]; DWORD dwSize=256; MsiGetProperty(hMsi, "Property1", szProp1, &dwSize); MsiGetProperty(hMsi, "Property2", szProp2, &dwSize); (the last argument of MsiGetProperty takes the size of the buffer szProp1 as input, and returns the number of characters copied into szProp1 as output;P) -- moved at 8:08 Monday 16th April, 2007

[CPallini]

True, even if it is more on the side of code-error than of code-horror one. :)

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.

[Haroon Sarwar]

:laugh:true, but this would fit perfectly in this forum if it was still called 'hall of shame' ;P....

[Rage]

Occured to me also once when playing with the registry, I think some of the Win32 API reading functions does this as well...

Company policy : no access to the internet but CP ~RaGE()

[DavidNohejl]

Well, it would fit in "Subtle bugs" forum nicely. But it is kinda WTF from design on API. It just begs to be (mis)used this way.

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"Throughout human history, we have been dependent on machines to survive. Fate, it seems, is not without a sense of irony. " - Morpheus "Real men use mspaint for writing code and notepad for designing graphics." - Anna-Jayne Metcalfe

[John R Shaw]

I can honestly say I have never seen that one before; which is saying a lot. :laugh:

INTP "Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

[Kochise]

Use C's "delayed assignement" : TCHAR szProp1[256]; TCHAR szProp2[256]; DWORD dwSize; MsiGetProperty(hMsi, "Property1", szProp1, **&(dwSize=256)**); MsiGetProperty(hMsi, "Property2", szProp2, **&(dwSize=256)**); or even : TCHAR szProp1[256]; TCHAR szProp2[256]; DWORD dwSizeProp1; DWORD dwSizeProp2; MsiGetProperty(hMsi, "Property1", szProp1, **&(dwSizeProp1=dwSizeProp2=256)**); MsiGetProperty(hMsi, "Property2", szProp2, **&dwSizeProp2**); It looks weird at first, but it works and avoid several bugs of this kind ! Kochise

In Code we trust !

[Haroon Sarwar]

Kochise wrote:

MsiGetProperty(hMsi, "Property1", szProp1, &(dwSize=256)); MsiGetProperty(hMsi, "Property2", szProp2, &(dwSize=256));

good idea...code is much nicer to look at :)

[John R Shaw]

:cool: I have never seen or thought of that before. I do not recommend it though, because the next, less experienced, C programmer that comes along will be saying WTF. :doh: I admit that I like the way it looks and consider it very creative. So I am very glad Kochise posted it. :-D

INTP "Program testing can be used to show the presence of bugs, but never to show their absence."Edsger Dijkstra

[Vivek Rajan]

>. MsiGetProperty(hMsi, "Property1", szProp1, &(dwSize=256)); Wow! Never seen that one before. Thanks

[Kochise]

Yeah, since I'm currently writing my own C compiler (not yet C++), I found very interresting coding tricks being just possible/allowed by the standard. It's fun, permisive and very powerful ! Kochise

In Code we trust !

[peterchen]

The beauty of C++ - there's always a nasty looking trick that one day will save your backus.

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