/* Note:Your choice is C IDE */
#include "stdio.h"
void main()
{
  struct student
  {
      char name[20];
      int result;
      char  grade;
  }myself[3]={{"zhang",80,'B'},
  {"li",90,'A'},{"wang",70,'C'}};
  int x;
  printf("input number 1 to 3:\n");
  scanf("%d",&x);
  switch(x)
  {
      case 1:printf("%ls,%d,%s",myself[1].name,myself[1].result,myself[1].grade);break;
      case 2:printf("%ls,%d,%s",myself[2].name,myself[2].result,myself[2].grade);break;
      case 3:printf("%ls,%d,%s",myself[3].name,myself[3].result,myself[3].grade);break;
      default:printf("reput number 1 to 2:\n");
      }
}

myself[3]数组下标是0～2

switch(x)
  {
      case 1:printf("%ls,%d,%s",myself[0].name,myself[0].result,myself[0].grade);break;
      case 2:printf("%ls,%d,%s",myself[1].name,myself[1].result,myself[1].grade);break;
      case 3:printf("%ls,%d,%s",myself[2].name,myself[2].result,myself[2].grade);break;
      default:printf("reput number 1 to 2:\n");
      }