Hi, thanks for the reply. I did not mean that I do not know how to use the function this way. For example, {#fun foo { `String' -- string , `Int' } -- string length -> IO () #} Where should I put the withCStringLen*? 2009/11/24 Thomas DuBuisson :

This isn't part of c2hs but part of Haskells FFI.

I suggest you see: http://haskell.org/ghc/docs/latest/html/libraries/base/Foreign-C-String.html...

Basically, if you need to call a C routine but your argument for it is a Haskell String then you can convert the Haskell String to a C string before passing:

withCStringLen "c2hs has nothing to do with this" ( \(strPtr, strLen) ->            some_imported_c_function strPtr strLen)

As for the code being different in c2hs - its the same except where you are using special c2hs macros {# ... #}.  If you haven't already seen the tutorial [1], I suggest you read that as a start.  Also, its easier to help if you include the code you mention.

Cheers, Thomas

[1] http://www.cse.unsw.edu.au/~chak/haskell/c2hs/docu/

On Tue, Nov 24, 2009 at 3:23 AM, Magicloud Magiclouds wrote:

...

Hi,  I am new to c2hs, while learning and trying it out, I am confused on how to use withCStringLen.  Well, I mean how to use it in .chs file, since the code style is a little different from .hs. Thanks. -- 竹密岂妨流水过 山高哪阻野云飞 _______________________________________________ C2hs mailing list C2hs@haskell.org http://www.haskell.org/mailman/listinfo/c2hs

-- 竹密岂妨流水过 山高哪阻野云飞