Hi Sylvain,
thank you for your response! I try to use this 2 lines
allocaArray (w*n) $ \var -> do
xs <- peekArray (w) var
to code
char **varnames = ccl_new_array (char *, w);
but it return [CString] not a [String]
On 04/29/2014 01:58 PM, Sylvain Henry wrote:
Hi,
"varnames" is an array of pointers, you cannot allocate it with
mallocBytes (n*100).
Try something like this (not tested):
mallocList :: [String] -> IO (Ptr CString)
mallocList xs = newArray =<< forM xs g
where
g x = do
b <- mallocBytes 100
pokeCString b x 99
return b
pokeCString :: CString -> String -> Int -> IO ()
pokeCString dst value maxLen = withCStringLen (take maxLen value) $
uncurry (copyArray dst)
-Sylvain
2014-04-29 13:11 GMT+02:00 Lamine <mohamadoulam...@gmail.com
<mailto:mohamadoulam...@gmail.com>>:
Hi,
I want to do write this C code in haskell code, but i have some pb:
int w ;
char **varnames = ccl_new_array (char *, w);
int i;
for (i = 0; i < w; i++)
{
varnames[i] = ccl_new_array (char, 100);
sprintf (varnames[i], "x%d", i);
}
I try this code unsing mallocList to (http://lpaste.net/report/712):
mallocList :: [CString] -> IO (Ptr CString)
mallocList xs = do let n = Prelude.length xs
p <- mallocBytes (n*100)
forM_ (Prelude.zip [0..] xs)
(uncurry (pokeByteOff p))
return p
let n = sizeOf(undefined :: CString)
allocaArray w $ \var -> do
xs <- peekArray (w*n) var
varnames <- mallocList xs
I have an error "segmentation fault(core dumped)".
can someone please help me? Thank you.
Lamine
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