将int数组转换为char数组并通过c ++中的memcpy返回

Question

I want to convert an array of int to an array of char and then back again, for serialization purposes. It does not need to work cross-platform.

I came up with

  //sample int array 
  int arr[] = {1,2,3,4,100};
  char char_arr[sizeof(arr)];
  //int arr to char arr
  memcpy(char_arr, arr, sizeof(arr));

  int newarr[sizeof(char_arr)/sizeof(int)];
  //char arr back to int arr
  memcpy(newarr, char_arr, sizeof(char_arr)/sizeof(int));

This does not seem to work however (newarr contains values different from arr). Any suggestions?

Answer 1

The third argument to memcpy is number of bytes ^* , not number of elements. So your second memcpy call is incorrect.

---

_{* Number of char s, technically.}

Answer 2

memcpy copies memory bytes, not array elements and thus does no array element conversion for you. If you want to convert an array of chars to an array of ints you might try std::copy which copies containers element by element.

int newarr[sizeof(char_arr)/sizeof(char_arr[0])]; 
std::copy(&char_arr[0], &char_arr[sizeof char_arr/sizeof char_arr[0]], newarr);