diff --git a/sys.cpp b/sys.cpp
new file mode 100644
index 0000000..4652bf0
--- /dev/null
+++ b/sys.cpp
@@ -0,0 +1,297 @@
+
+#include<sys.h>
+void studentinit(student t)
+{
+	t.num = 0;
+	t.math = 0;
+	t.english = 0;
+	t.sum_score = 0;
+}
+int student_show_menu() //显示菜单
+{
+	int i = 0;
+	printf("\n");
+	for (i = 1; i < 50; i++)
+		printf("*");
+	printf("\n");
+	printf("欢迎使用学生信息管理系统\n\n");
+	printf("1.输入全部学生信息\n");
+	printf("2.读取全部学生信息\n");
+	printf("3.按姓名查询学生\n");
+	printf("4.按学号查询学生\n");
+	printf("5.按学号排序学生\n");
+	printf("6.按总成绩排序学生\n");
+	printf("7.添加学生信息\n");
+	printf("8.删除学生信息\n");
+	printf("0.退出系统\n\n");
+	for ( i = 1; i < 50; i++)
+		printf("*");
+	printf("\n");
+	return 0;
+}
+
+void student_input(LNode* head) //输入学生信息
+{
+	int n=0;
+	int i = 0;
+	printf("\n【1】输入全部学生信息\n");
+	printf("输入学生个数：");
+	scanf_s("%d", &n);
+	LNode* p;
+	LNode* r = head;
+	printf("请输入学生信息：\n");
+	for (i = 0; i < n; i++)
+	{
+		p = (LNode*)malloc(sizeof(LNode));
+		p->next = NULL;
+		printf("请输入学生姓名：");
+		scanf_s("%s", p->data.names, maxsize);
+		printf("请输入学号：");
+		scanf_s("%d", &p->data.num);
+		printf("请输入学生数学成绩：");
+		scanf_s("%d", &p->data.math);
+		printf("请输入学生英语成绩：");
+		scanf_s("%d", &p->data.english);
+		//int *sum = p->data.sum_score;
+		p->data.sum_score = p->data.math + p->data.english;
+		r->next = p;
+		r = r->next;
+		//free(p);		//若使用了此句，后续输出列表会出错。因为每个空间的数据都是有用的，所以不用free。
+		printf("\n");
+	}
+	printf("\n添加学生信息成功！\n");
+	//return head;
+}
+
+void student_show(LNode* head) //读取全部学生信息
+{
+	printf("\n【2】读取全部学生信息\n");
+	LNode* p;
+	p = head;
+	if (p->next == NULL)
+	{
+		printf("\n当前没有任何学生信息记录! 请输入学生信息。\n");
+		return;
+	}
+	printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
+	while (p->next != NULL)
+	{
+		p = p->next;
+		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n",
+			p->data.names, p->data.num, p->data.math, p->data.english, p->data.sum_score);
+	}
+}
+
+int name_find(LNode* head, student f) //按姓名查询学生
+{
+	printf("【3】按姓名查询学生\n");
+	LNode* p;
+	p = head;
+	printf("请输入查找学生姓名：");
+	scanf_s("%s", f.names, maxsize);
+	while ((p->next != NULL) && strcmp(f.names, p->data.names)) //str1=str2，则返回零；若str1!=str2，则返回正数
+	{
+		p = p->next;
+	}
+	if ((p->next == NULL) && strcmp(f.names, p->data.names))
+	{
+		printf("\n抱歉，没有找到该学生的信息! \n");
+		return 0;
+	}
+	else
+	{
+		printf("\n查找学生信息成功！\n");
+		printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
+		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n",
+			p->data.names, p->data.num, p->data.math, p->data.english, p->data.sum_score);
+		return 1;
+	}
+}
+
+int num_find(LNode* head, student f2) //按学号查找学生
+{
+	printf("【4】按学号查询学生\n");
+	LNode* p;
+	p = head;
+	printf("请输入查找学生学号：");
+	scanf_s("%d", &f2.num);
+	while ((p->next != NULL) && (p->data.num != f2.num))
+	{
+		p = p->next;
+	}
+	if ((p->next == NULL) && (p->data.num != f2.num))
+	{
+		printf("\n抱歉，没有找到该学生的信息! \n");
+		return 0;
+	}
+	else
+	{
+		printf("\n查找学生信息成功！\n");
+		printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
+		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n",
+			p->data.names, p->data.num, p->data.math, p->data.english, p->data.sum_score);
+		return 1;
+	}
+}
+
+void num_seq(LNode* head) //按学号排序
+{
+	printf("\n【5】按学号排序学生\n");
+	LNode* newhead, * rear;
+	newhead = head->next;
+	rear = NULL;
+	if (newhead == NULL || newhead->next == NULL)
+	{
+		printf("\n当前没有任何学生信息记录! 请输入学生信息。\n");
+		return;
+	}
+	while (newhead != rear)
+	{
+		while (newhead->next != rear)
+		{
+			if (newhead->data.num > newhead->next->data.num)
+			{
+				int temp = newhead->data.num;
+				newhead->data.num = newhead->next->data.num;
+				newhead->next->data.num = temp;
+				int temp1 = newhead->data.math;
+				newhead->data.math = newhead->next->data.math;
+				newhead->next->data.math = temp1;
+				int temp2 = newhead->data.english;
+				newhead->data.english = newhead->next->data.english;
+				newhead->next->data.english = temp2;
+				int temp3 = newhead->data.sum_score;
+				newhead->data.sum_score = newhead->next->data.sum_score;
+				newhead->next->data.sum_score = temp3;
+				//char temp4_str = gets(newhead->data.names, sizeof(char));
+				//char *temp4 = newhead->data.names; //先替换了此值，故第二个strcpy使用*temp4已经是新值了。
+				student str;
+				strcpy_s(str.names, maxsize, newhead->data.names);
+				//gets_s(newhead->data.names,maxsize);
+				//newhead->data.names = newhead->next->data.names;
+				strcpy_s(newhead->data.names, maxsize, newhead->next->data.names);
+				//newhead->next->data.names = temp4;
+				strcpy_s(newhead->next->data.names, maxsize, str.names);
+			}
+			newhead = newhead->next;
+		}
+		rear = newhead;
+		newhead = head->next;
+	}
+	printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
+	while (head->next != NULL)
+	{
+		head = head->next;
+		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n",
+			head->data.names, head->data.num, head->data.math, head->data.english, head->data.sum_score);
+	}
+}
+
+void sum_seq(LNode* head) //按总成绩排序
+{
+	printf("\n【6】按总成绩排序学生\n");
+	LNode* newhead, * rear;
+	newhead = head->next;
+	rear = NULL;
+	if (newhead == NULL || newhead->next == NULL)
+	{
+		printf("\n当前没有任何学生信息记录! 请输入学生信息。\n");
+		return;
+	}
+	while (newhead != rear)
+	{
+		while (newhead->next != rear)
+		{
+			if (newhead->data.sum_score < newhead->next->data.sum_score)
+			{
+				int temp = newhead->data.num;
+				newhead->data.num = newhead->next->data.num;
+				newhead->next->data.num = temp;
+				int temp1 = newhead->data.math;
+				newhead->data.math = newhead->next->data.math;
+				newhead->next->data.math = temp1;
+				int temp2 = newhead->data.english;
+				newhead->data.english = newhead->next->data.english;
+				newhead->next->data.english = temp2;
+				int temp3 = newhead->data.sum_score;
+				newhead->data.sum_score = newhead->next->data.sum_score;
+				newhead->next->data.sum_score = temp3;
+				student str;
+				strcpy_s(str.names, strlen(newhead->data.names) + 1, newhead->data.names);
+				strcpy_s(newhead->data.names, strlen(newhead->next->data.names) + 1, newhead->next->data.names); //注意缓冲区长度，strlen()函数计算的字符串长度是不包括'\0’
+				strcpy_s(newhead->next->data.names, strlen(str.names) + 1, str.names);
+			}
+			newhead = newhead->next;
+		}
+		rear = newhead;
+		newhead = head->next;
+	}
+	printf("\n姓名\t\t学号\t\t数学成绩\t英语成绩\t总成绩\t\t\n");
+	while (head->next != NULL)
+	{
+		head = head->next;
+		printf("%s\t\t%d\t\t%d\t\t%d\t\t%d\t\t\n",
+			head->data.names, head->data.num, head->data.math, head->data.english, head->data.sum_score);
+	}
+}
+
+void stu_insert(LNode* head, student in) //增加学生信息
+{
+	printf("\n【7】添加学生信息\n");
+	printf("请输入学生信息：\n");
+	printf("请输入学生姓名：");
+	scanf_s("%s", in.names, maxsize);
+	printf("请输入学号：");
+	scanf_s("%d", &in.num);
+	printf("请输入学生数学成绩：");
+	scanf_s("%d", &in.math);
+	printf("请输入学生英语成绩：");
+	scanf_s("%d", &in.english);
+	in.sum_score = in.math + in.english;
+	LNode* stu, * r;
+	r = head;
+	int d, dp = 0;
+	printf("请输入要插入的位置：");
+	scanf_s("%d", &d);
+	while ((r != NULL) && (dp < d - 1))
+	{
+		r = r->next;
+		dp = dp + 1;
+	}
+	if (r == NULL)
+	{
+		printf("\n插入错误，请重新输入。\n");
+		return;
+	}
+	stu = (LNode*)malloc(sizeof(LNode));
+	stu->data = in;
+	stu->next = r->next;
+	r->next = stu;
+	printf("\n插入信息成功！\n");
+}
+
+void stu_del(LNode* head, student* dl) //删除学生信息
+{
+	printf("\n【8】删除学生信息\n");
+	LNode* stu, * r;
+	r = head;
+	int d, dp = 0;
+	printf("请输入要删除的位置：");
+	scanf_s("%d", &d);
+	while ((r->next != NULL) && (dp < d - 1))
+	{
+		r = r->next;
+		dp++;
+	}
+	if (r->next == NULL)
+	{
+		printf("\n删除错误，请重新输入。\n");
+		return;
+	}
+	stu = r->next;
+	r->next = stu->next;
+	*dl = stu->data; //此时应为*dl ,下面printf才能顺利输出
+	free(stu);
+	printf("删除%s成功!\n", dl->names);
+	//return;
+}
\ No newline at end of file