Yes, see the documentation for useAsCString [0]. [0] http://hackage.haskell.org/package/bytestring-0.10.4.0/docs/Data-ByteString.... Erik On Fri, Sep 19, 2014 at 6:32 AM, ye yan wrote:

I have been play around with Haskell FFI. My question is for ByteString (Strict) is there a trailing null append to it when pass to it C functions?

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Sorry, accidentally clicked post; in haskell FFI c++ side Blob db; try { sb.update(src, src_len); } catch (Magick::Exception &error) { //do something with error } if I compile my program in to c++ program this code works perfectly fine. The exception can be handled correctly. But if link this piece of code into haskell (main is in haskell side), the exception handle code will never be triggered. However if I change the code to Blob db; try { sb.update(src, src_len); } catch (...) { //can really do any thing but tell user this function failed } the exception handle part can be triggered in this way. My question is : how can I catch exception without using (...) in Haskell FFI? On Friday, September 19, 2014 2:02:29 PM UTC+9:30, ye yan wrote:

I have been play around with Haskell FFI. My question is for ByteString (Strict) is there a trailing null append to it when pass to it C functions?