#include     void main()
{
        union myfloat{
                float f;
                unsigned char cc[4];
        };            union myfloat fnum;
        fnum.cc[0]=0x00;
        fnum.cc[1]=0x00;
        fnum.cc[2]=0x00;
        fnum.cc[3]=0x40;  
        printf("%f\n", fnum.f);
}
 

void TestFloat()
{
  union myFloat {
    float mF; // 實際的 float 值
    struct FloatStruct {
      long mExponent : 8;
      long mMantissa : 23;
      long mSign : 1;
    } mStFloat;
  };      myFloat aF;
  aF.mF = 0.f;
  aF.mF = -1.2f;
  aF.mF = 1.2f;
}

  union myFloat {
    float mF; // 實際的 float 值
    struct FloatStruct {
      unsigned long mMantissa : 23;
      unsigned long mExponent : 8;
      unsigned long mSign : 1;
    } mStFloat;
  };
  myFloat aF;
  aF.mF = -16.f; // mSign=1, mExponent =0x83, mMantissa=0
  aF.mStFloat.mSign = 0; // mF =16.0
  aF.mStFloat.mExponent = 0x84; // aF.mf = 32.0