Detecting File Endianness

1#include <iostream>
2#include "SDL.h"
3
4int main() {
5  // When writing the file:
6  SDL_RWops* WriteHandle{
7    SDL_RWFromFile("data.bin", "wb")};
8  if (!WriteHandle) {
9    std::cout <<
10      "Error opening file for writing: "
11      << SDL_GetError() << '\n';
12    return 1;
13  }
14
15  // Write a known magic number (0x12345678)
16  Uint32 MagicNumber{0x12345678};
17  SDL_WriteLE32(WriteHandle, MagicNumber);
18
19  // Write your actual data...
20
21  SDL_RWclose(WriteHandle);
22
23  // When reading the file:
24  SDL_RWops* ReadHandle{
25    SDL_RWFromFile("data.bin", "rb")};
26  if (!ReadHandle) {
27    std::cout <<
28      "Error opening file for reading: "
29      << SDL_GetError() << '\n';
30    return 1;
31  }
32
33  // Try reading as little-endian first
34  Uint32 ReadMagic{SDL_ReadLE32(ReadHandle)};
35
36  if (ReadMagic == 0x12345678) {
37    std::cout <<
38      "File is in little-endian format\n";
39  } else {
40    // Rewind and try big-endian
41    SDL_RWseek(ReadHandle, 0, RW_SEEK_SET);
42    ReadMagic = SDL_ReadBE32(ReadHandle);
43
44    if (ReadMagic == 0x12345678) {
45      std::cout <<
46        "File is in big-endian format\n";
47    } else {
48      std::cout << "Unknown file format\n";
49    }
50  }
51
52  SDL_RWclose(ReadHandle);
53  return 0;
54}