Defining unions and structures in c51

union {
  unsigned char Ch; //"unsigned number
  unsigned char CHR[4]; //"unsigned array
  unsigned long I; //"unsigned integer
  long L; //"signed long integer
  float F; //"floating point number
    }EEP;

float shu;

 EEP.F =shu;        //

Structure

struct realti
 {
    uchar Second;
   uchar Minute;
   uchar Hour;
    uchar Day;
    uchar Month;
    uchar Week;
    uchar Year;
  uchar kzz; //8 bytes must be written continuously, otherwise it cannot be written
 };
 struct realti RealTime; //struct realti RealTime[3];

or:

struct realti
 {
    uchar Second;
   uchar Minute;
   uchar Hour;
    uchar Day;
    uchar Month;
    uchar Week;
    uchar Year;
  uchar kzz; //8 bytes must be written continuously, otherwise it cannot be written
 }RealTime; //RealTime[3];
 or:

struct {
    uchar Second;
   uchar Minute;
   uchar Hour;
    uchar Day;
    uchar Month;
    uchar Week;
    uchar Year;
  uchar kzz; // Continuous writing must be 8 bytes, otherwise it cannot be written
 }RealTime; // RealTime[3];

usage:

RealTime.Second = 0X30;
      RealTime.Minute = 0X11;
      RealTime.Hour = 0X15;
       RealTime.Day = 0X06;
       RealTime.Month = 0X03;
       RealTime.Week = 0X05;
     RealTime.Year = 0X09;
     RealTime.kzz = 0X00;
     DS1302Write_Time(&RealTime.Second); //Write clock data to DS1302 (multi-byte mode)

DS1302Read_Time(&RealTime.Second); //Read the first address of DS1302 clock data RealTime.Second

void DS1302Read_Time(uchar *pSecDa) //Read DS1302 clock data
{
  uchar i;
  DS1302_Open();//Open DS1302
  DS1302_Write(0xbf); /* 0xbf: clock multi-byte read command*/
  for (i=0; i<8; i++) //Continuous writing must be 8 bytes, otherwise it cannot be written
   {
   *pSecDa = DS1302_Read(); /* Read 1Byte data*/
   pSecDa++;
   }
  DS1302_Close();//Close DS1302
}

void DS1302Write_Time(uchar *pSecDa) //Write clock data to DS1302 (multi-byte mode)
{
  uchar i;
  DS1302Byte_Write(0x8e,0x00); /* Control command, WP=0, write enable*/
  DS1302_Open();//Open DS1302
  DS1302_Write(0xbe); /* 0xbe: clock multi-byte write command*/
  for (i=0; i<8; i++) /*8Byte = 7Byte clock data + 1Byte control*/
   {
    DS1302_Write(*pSecDa);/* Write 1Byte data*/
    pSecDa++;
   } 
  DS1302_Close();//Close DS1302
}