fixed array concate issue

Author: tusharad

FFI/ffi_examples

@@ -21,6 +21,7 @@ foreign import ccall "intToString" c_intToString :: CInt -> CString
 foreign import ccall "bubbleSort" c_bubbleSort :: Ptr CInt -> CInt -> IO()
 foreign import ccall "toUpper" c_toUpper :: CString -> IO()
 foreign import ccall "addTwoArrays" c_addTwoArrays:: Ptr CInt -> CInt -> Ptr CInt -> Int -> IO (Ptr CInt)
+foreign import ccall "addThreeArrays" c_addThreeArrays:: Ptr CInt -> CInt -> Ptr CInt -> Int -> Ptr CInt -> Int -> IO (Ptr CInt)
 
 swapTwoNums :: Int -> Int -> (Int,Int)
 swapTwoNums x y = unsafePerformIO $ do
@@ -53,13 +54,31 @@ toUpper str = do
   withCString str $ \str2 -> do
     c_toUpper str2
 
+addThreeArrays :: [Int32] -> [Int32] -> [Int32] -> [Int32]
+addThreeArrays xs ys zs = unsafePerformIO $ do
+  let len1 = length xs
+  let len2 = length ys
+  let len3 = length zs
+  allocaBytes (len1*4) $ \ptr1 -> do
+    pokeArray ptr1 xs
+    allocaBytes (len2*4) $ \ptr2 -> do
+      pokeArray ptr2 ys
+      allocaBytes (len3*4) $ \ptr3 -> do
+        pokeArray ptr3 zs
+        arrPtr <- c_addThreeArrays (castPtr ptr1) (fromIntegral len1) (castPtr ptr2) (fromIntegral len2) (castPtr ptr3) (fromIntegral len3)
+        foreignPtr <- newForeignPtr p_free arrPtr
+        array <- withForeignPtr foreignPtr $ \ptr -> peekArray (len1+len2+len3) (castPtr ptr)
+        return array
+
 addTwoArrays :: [Int32] -> [Int32] -> [Int32]
 addTwoArrays xs ys = unsafePerformIO $ do
   let len1 = length xs
   let len2 = length ys
-  alloca $ \ptr1 -> do
+  allocaBytes (len1*4) $ \ptr1 -> do
     pokeArray ptr1 xs
-    alloca $ \ptr2 -> do
+    print $ unsafePerformIO $ peek (plusPtr ptr1 8 :: Ptr Int32)
+    print $ unsafePerformIO $ peek ptr1
+    allocaBytes (len2*4) $ \ptr2 -> do
       pokeArray ptr2 ys
       arrPtr <- c_addTwoArrays (castPtr ptr1) (fromIntegral len1) (castPtr ptr2) (fromIntegral len2)
       foreignPtr <- newForeignPtr p_free arrPtr
@@ -88,4 +107,5 @@ main = do
     -- toUpper
     toUpper "tushar"
     -- merge array
-    print $ addTwoArrays [4,5,6,45,76,57] [2,3,3]
+    print $ addTwoArrays [1,2,3] [4,5,6]
+    print $ addThreeArrays [1,2,3] [4,5,6] [7,8,9]

FFI/ffi_examples.hs

@@ -36,18 +36,32 @@ char* intToString(int x){
   return num;
 }
 
-
-int* addTwoArrays(int* arr1,int n1,int* arr2,int n2){
-  int num = n1+n2;
+int* addThreeArrays(int* arr1,int n1,int* arr2,int n2,int* arr3,int n3){
+  int num = n1+n2+n3;
   int* arr = malloc(num*sizeof(int*));
   int k =0;
-  
+  for(int i = 0;i < n1;i++){
+    arr[k++] = arr1[i];
+  }
   for(int i = 0;i < n2;i++){
     arr[k++] = arr2[i];
   }
+  for(int i = 0;i < n3;i++){
+    arr[k++] = arr3[i];
+  }
+  return arr;
+}
+
+int* addTwoArrays(int* arr1,int n1,int* arr2,int n2){
+  int num = n1+n2;
+  int* arr = malloc(num*sizeof(int*));
+  int k =0;
   for(int i = 0;i < n1;i++){
     arr[k++] = arr1[i];
   }
+  for(int i = 0;i < n2;i++){
+    arr[k++] = arr2[i];
+  }
   return arr;
 }