Implementations[edit]

Java[edit]

Java virtual machine always used big-endian, Intel x86 used little-endian.

 public class Swab {
  public final static int swabInt(int v) {
    return  (v >>> 24) | (v << 24) | 
      ((v << 8) & 0x00FF0000) | ((v >> 8) & 0x0000FF00);
    }

  public static void main(String argv[]) {
    //  before 0x01020304
    //  after  0x04030201
    int v = 0x01020304;
    System.out.println("before : 0x" + Integer.toString(v,16));
    System.out.println("after  : 0x" + Integer.toString(swabInt(v),16));
    }
  }

Ruby[edit]

def change_endian(input)
  output = 0
  4.times do |i|
    input, r = input.divmod(256)
    output = output * 256 + r
  end
  output
end

before = 0x01020304
after  = change_endian(before)
printf "before : %#010x\n", before   #=> before : 0x01020304
printf "after  : %#010x\n", after    #=> after  : 0x04030201