If you are writing binary data from memory, _and_ want to make sure any system can read it no matter what endianness it uses, you might need something like this

If you are writing binary data from memory, _and_ want to make sure any system can read it no matter what endianness it uses, you might need something like this: buf[0] = (data >> 24) & 0xFF; buf[1] = (data >> 16) & 0xFF; buf[2] = (data >> 8) & 0xFF; buf[3] = data & 0xFF; and if you want this code to work on all systems (including wide-char ones), you need to make sure fwrite truncates too.