diff --git a/学籍管理系统 步骤3.c b/学籍管理系统 步骤3.c
new file mode 100644
index 0000000..5fb6658
--- /dev/null
+++ b/学籍管理系统 步骤3.c	
@@ -0,0 +1,78 @@
+#include<stdio.h>
+#define N 3
+
+struct stu_info
+{
+	int num;
+	float math,physics,english,sum,average;
+};
+
+struct stu_info stu[N];
+
+void sort(struct stu_info *stu)
+{
+	int i,j;
+	struct stu_info tmp;
+	for(i=0;i<N;i++)
+	{
+		for(j=0;j<N-i-1;j++)
+		{
+			if((stu+j)->average>(stu+j+1)->average)
+			{
+				tmp = *(stu+j);
+				*(stu+j) = *(stu+j+1);
+				*(stu+j+1) = tmp;
+			} 
+		}
+	}
+	return;
+}
+
+void input(void)
+{
+	int i;
+	for(i=0;i<N;i++)
+	{
+		scanf("%d",&stu[i].num);
+		scanf("%f",&stu[i].math);
+		scanf("%f",&stu[i].physics);
+		scanf("%f",&stu[i].english);
+		stu[i].sum=stu[i].math+stu[i].physics+stu[i].english;
+		stu[i].average=stu[i].sum/3;
+	}
+	sort(stu);
+	for(i=0;i<N;i++)
+	{
+		printf("%d,%.1f,%.1f\n",stu[i].num,stu[i].sum,stu[i].average);
+	}
+	return;
+} 
+
+int main()
+{
+	char in;
+	printf("                              1.Input\n");
+	printf("                              2.Output\n");
+	printf("                              3.Order\n");
+	printf("                              4.Quit\n");
+	scanf("%c",&in);
+	switch(in)
+	{
+		case('i'):
+			printf("Please input info of the three students:\n"); 
+			input();
+			break;
+		case('o'):
+			printf("You are trying to Output info\n");
+			break;
+		case('m'):
+			printf("You are trying to Make things ordered\n");
+			break;
+		case('q'):
+			printf("You are about to Quit\n");
+			break;
+		default:
+			printf("Wrong input\n");
+	}
+	return 0;
+}