Add step3

step3

@@ -0,0 +1,55 @@
+#include<stdio.h>
+struct Student
+{
+	int id;
+	float gs;
+	float dw;
+	float yy;
+	float sum;
+	float aver;
+}stu[3],temp;
+int main()
+{
+	printf("                              1.Input\n");
+	printf("                              2.Output\n");
+	printf("                              3.Order\n");
+	printf("                              4.Quit\n");
+	int i=0,j=0;
+	char x;
+	scanf("%c",&x);
+	switch(x){
+		case 'o':printf("You are trying to Output info");break;
+		case 'm':printf("You are trying to Make things ordered");break;
+		case 'q':printf("You are about to Quit");break;
+		case 'i':printf("Please input info of the three students:\n");
+			for(i=0;i<3;i++)
+			{
+				scanf("%d\n",&stu[i].id);
+				scanf("%f\n",&stu[i].gs);
+				scanf("%f\n",&stu[i].dw);
+				scanf("%f\n",&stu[i].yy);
+				stu[i].sum=stu[i].gs+stu[i].dw+stu[i].yy;
+				stu[i].aver=stu[i].sum/3;
+			}
+			for( i=0;i<3;i++)//排序操作 
+			{
+				for( j=0;j<3-i-1;j++)
+				{
+					if(stu[j].sum>stu[j+1].sum)
+					{
+					temp=*(stu+j);
+					*(stu+j)=*(stu+j+1);
+					*(stu+j+1)=temp;
+				    }
+				}
+			}
+			for(i=0;i<3;i++)
+			{
+				printf("学号 %d，总成绩 %.1f,平均成绩 %.1f\n",stu[i].id,stu[i].sum,stu[i].aver);
+			}
+			break;
+			
+		default:printf("Wrong input\n");break;
+	}
+	return 0;
+}