the struct of c lauguage test code

#include <stdio.h>

typedef struct i
{
    int a;
    char b;
    double c;
 
}u;

int main()
{  u j;                    // the struct define 1.
   struct i k;          // the struct define 1.
    j.a=1;
    k.b=3;
 
   printf("%d\n",j.a);
   printf("%d\n",k.b );

 /* the end of run is 1and 3           */