diff --git a/8.cpp b/8.cpp
new file mode 100644
index 0000000..f954263
--- /dev/null
+++ b/8.cpp
@@ -0,0 +1,156 @@
+#include<stdio.h>
+#include<string.h>
+void Menu()
+{
+	printf("1.input\n");
+	printf("2.delete\n");
+	printf("3.select\n");
+	printf("4.order\n");
+	printf("5.output\n");
+	printf("6.quit\n");
+	printf("please input your option\n");
+}
+struct Info
+{
+	char num[6], name[7];
+	int cls;
+	float math, phy, eng, sum;
+}arr[4], ins, mod;
+void Input(int i)
+{
+	void Option();
+	printf("id ");
+	scanf("%s", arr[i].num);
+	printf("class ");
+	scanf("%d", &arr[i].cls);
+	printf("name ");
+	scanf("%s", arr[i].name);
+	printf("score1 ");
+	scanf("%f", &arr[i].math);
+	printf("score2 ");
+	scanf("%f", &arr[i].phy);
+	printf("score3 ");
+	scanf("%f", &arr[i].eng);
+	arr[i].sum = arr[i].math + arr[i].phy + arr[i].eng;
+	printf("continue?\n");
+	char yon[4];
+	scanf("%s", yon);
+	if (strcmp(yon, "yes") == 0)
+		Input(i + 1);
+	else
+		Option();
+}
+void Output(int i)
+{
+	printf("%s ", arr[i].num);
+	printf("%d ", arr[i].cls);
+	printf("%s ", arr[i].name);
+	printf("%.1f %.1f %.1f ", arr[i].math, arr[i].phy, arr[i].eng);
+	printf("%.1f", arr[i].sum);
+	printf("\n");
+}
+void Rank(int s)
+{
+	for (int i = 0; i < s; i++)
+		for (int j = s - 1; j > i; j--)
+		{
+			if (arr[j].cls < arr[j - 1].cls)
+			{
+				struct Info temp = arr[j];
+				arr[j] = arr[j - 1];
+				arr[j - 1] = temp;
+			}
+		}
+	for (int i = 0; i < s; i++)
+		for (int j = s - 1; j > 0; j--)
+		{
+			if (arr[j].cls == arr[j - 1].cls && arr[j].sum > arr[j - 1].sum)
+			{
+				struct Info temp = arr[j];
+				arr[j] = arr[j - 1];
+				arr[j - 1] = temp;
+			}
+		}
+}
+void Del(int* p)
+{
+	void Option();
+	char str[7];
+	scanf("%s", str);
+	for (int i = 0; i < *p; i++)
+	{
+		if (strcmp(str, arr[i].num) == 0 || strcmp(str, arr[i].name) == 0)
+		{
+			for (int j = i + 1; j < *p; j++)
+				arr[j - 1] = arr[j];
+			(*p)--;
+		}
+	}
+	for (int j = 0; j < *p; j++)
+		Output(j);
+	printf("continue?\n");
+	char yon[4];
+	scanf("%s", yon);
+	if (strcmp(yon, "yes") == 0)
+		Del(p);
+	else
+		Option();
+}
+void Find(int s)
+{
+	void Option();
+	char n[6];
+	scanf("%s", n);
+	int l = strlen(n);
+	if (l > 2)
+	{
+		for (int i = 0; i < s; i++)
+			if (strcmp(arr[i].num, n) == 0)
+				Output(i);
+	}
+	else
+	{
+		int c = 10 * (n[0] - '0') + n[1] - '0';
+		for (int i = 0; i < s; i++)
+			if (arr[i].cls == c)
+				Output(i);
+	}
+	char yon[4];
+	scanf("%s", yon);
+	if (strcmp(yon, "yes") == 0)
+		Find(s);
+	else
+		Option();
+}
+void Option()
+{
+	Menu();
+	int c;
+	scanf("%d", &c);
+	int s = 3;
+	int* p = &s;
+	switch (c)
+	{
+	case 1:Input(0); break;
+	case 2:Del(p); break;
+	case 3:Find(s); break;
+	case 4: {
+		Rank(s);
+		for (int i = 0; i < s; i++)
+			Output(i);
+		Option();
+		break;
+	}
+	case 5: {
+		for (int i = 0; i < s; i++)
+			Output(i);
+		Option();
+		break;
+	}
+	case 6:break;
+	}
+}
+int main()
+{
+	Option();
+}