接收从键盘输入的一个班的学生成绩，并存放于50字的grade数组中，其中grade+i保存为i+1的学生的成绩。然后根据grade中的学生成绩，把学生名次填入50字的rank数组中，其中rank+i的内容是学号为i+1学生的名次。再按学号顺序把名次从终端上显示出来。-Receiving input from the keyboard of a class of student achievement, and stored in the array of 50 words grade, which grade+i save the results of the i+1 students. Grade in student achievement, student ranking fill 50 words rank array, which rank+i the student number is the ranking of i+1 students. Then number the order of ranking from the terminal.