union{ int Word; struct { char Byte1:8; char Byte2:8; }structBytes; }myVar; myVar.Word = 0xFFFF; // myVar = 1111111111111111 myVar.structBytes.Byte1 = 0xF0; // myVar = 0000000011110000 myVar.structBytes.Byte2 = 0xF0; // myVar = 1111000011110000