diff --git a/task7.cpp b/task7.cpp
new file mode 100644
index 0000000..5397499
--- /dev/null
+++ b/task7.cpp
@@ -0,0 +1,276 @@
+#include <stdio.h>
+#include <string.h>
+
+#define MARK 10
+int input=0;
+char range[17];
+//定义结构体
+struct Student
+{
+	int ID;//学号 
+	int classes;
+	char name[8];
+	float math_grade;
+	float physics_grade;
+	float English_grade;
+	float sum;
+};
+
+int pow10(int M)
+{
+	int num=1;
+	for(int i=1;i<=M;i++)
+	{
+		num*=10;
+	}
+	
+	return num;
+}
+
+//对结构体中的从start同学到end同学排序
+void Sort(struct Student information[8],int start,int end)
+{
+	//先班级 
+	for(int i=start;i<=end;i++)
+	{
+		for(int j=start;j<=end-1;j++)
+		{
+			if(information[j].classes>information[j+1].classes)
+			{
+				struct Student tmp=information[j];
+				information[j]=information[j+1];
+				information[j+1]=tmp;
+			}
+		}
+	}
+	//同班同学再成绩 
+	for(int i=start;i<=end;i++)
+	 {
+	 	int con=0;//记录连续了几人 
+	 	for(int j=1;j<=end-i;j++)
+	 	{
+	 		if(information[i].classes==information[i+j].classes)
+	 		{con=j;
+			 }
+			 else
+			 {
+			 break;
+			 }
+		 }
+			 
+		 if(con)//有人是同班同学，在此内排序 
+		 {
+		 	for(int m=i;m<=i+con;m++)
+			{
+				for(int n=i;n<=i+con-1;n++)
+				{
+					if(information[n].sum<information[n+1].sum)
+			 		{
+						struct Student tmp=information[n];
+						information[n]=information[n+1];
+						information[n+1]=tmp;
+					 }
+				 }
+			 }
+		 }	 
+		 i=i+con;
+	  } 
+}
+
+
+//按格式输出 
+void output(struct Student information[8],int start,int end)
+{
+	for(int i=start;i<=end;i++)
+	{
+		printf("%d %d ",information[i].ID,information[i].classes);
+		for(int j=0;information[i].name[j]!='\0';j++)
+		{
+			printf("%c",information[i].name[j]);
+		}
+		printf(" %.1f %.1f %.1f\n",information[i].math_grade,\
+		information[i].physics_grade,information[i].English_grade);
+	}
+}
+
+int main()
+{
+	struct Student information[8];
+	//已有7个同学的信息
+	information[0].ID=10001;strcpy(information[0].name, "Zhang");
+	information[0].classes=11;information[0].math_grade=99.5;
+	information[0].physics_grade=88.5;information[0].English_grade=89.5;
+	information[0].sum=99.5+88.5+89.5;
+	
+	information[1].ID=10002;strcpy(information[1].name, "Yang");
+	information[1].classes=12;information[1].math_grade=77.9;
+	information[1].physics_grade=56.5;information[1].English_grade=87.5;
+	information[1].sum=77.9+56.5+87.5;
+	
+	information[2].ID=10003;strcpy(information[2].name, "Liang");
+	information[2].classes=11;information[2].math_grade=92.5;
+	information[2].physics_grade=99.0;information[2].English_grade=60.5;
+	information[2].sum=92.5+99.0+60.5;
+	
+	information[3].ID=10004;strcpy(information[3].name, "Cai");
+	information[3].classes=11;information[3].math_grade=89.6;
+	information[3].physics_grade=56.9;information[3].English_grade=90.5;
+	information[3].sum=89.6+56.9+90.5;
+	
+	information[4].ID=10005;strcpy(information[4].name, "Fu");
+	information[4].classes=14;information[4].math_grade=55.6;
+	information[4].physics_grade=67.9;information[4].English_grade=98.9;
+	information[4].sum=55.6+67.9+98.9;
+	
+	information[5].ID=10006;strcpy(information[5].name, "Mao");
+	information[5].classes=12;information[5].math_grade=22.1;
+	information[5].physics_grade=45.9;information[5].English_grade=99.2;
+	information[5].sum=22.1+45.9+99.2;
+	
+	information[6].ID=10007;strcpy(information[6].name, "Zhan");
+	information[6].classes=13;information[6].math_grade=35.6;
+	information[6].physics_grade=67.9;information[6].English_grade=88.0;
+	information[6].sum=35.6+67.9+88.0;
+	
+	scanf("%d%s",&input,range);//输入类别和查询范围 
+	struct Student new_information[8];
+	
+	//下面分类讨论 
+	if(input==1)
+	{
+		int start=0;int end=0;
+		start=10*(range[0]-'0')+(range[1]-'0');
+		end=10*(range[3]-'0')+(range[4]-'0');
+		int i=0;int j=0;
+		for(int i=0;i<=6;i++)
+		{
+			if(information[i].classes<=end&&information[i].classes>=start)
+			{
+				new_information[j]=information[i];
+				j++;//最后会有j个被选入 
+			}
+		 } //筛选出了所有学生
+		 
+		 //排序 
+		Sort(new_information,0,j-1);
+		output(new_information,0,j-1);
+	}
+	else if(input==2)
+	{
+		int start=0;int end=0;
+		start=10000*(range[0]-'0')+1000*(range[1]-'0')+100*(range[2]-'0')\
+		+10*(range[3]-'0')+(range[4]-'0');
+		end=10000*(range[6]-'0')+1000*(range[7]-'0')+100*(range[8]-'0')\
+		+10*(range[9]-'0')+(range[10]-'0');
+		int i=0;int j=0;
+		for(int i=0;i<=6;i++)
+		{
+			if(information[i].ID<=end&&information[i].ID>=start)
+			{
+				new_information[j]=information[i];
+				j++;//最后会有j个被选入 
+			}
+		 } //筛选出了所有学生
+		 
+		 //排序 
+		Sort(new_information,0,j-1);
+		output(new_information,0,j-1);
+	}
+	else if(input==3)
+	{
+		int j=0;
+		
+		for(int i=0;i<=6;i++)
+		{
+			int judge=1;//判断是否缩写吻合的标志 
+			for(int k=0;range[k]!='*';k++)
+			{
+				if(information[i].name[k]!=range[k])
+				{
+					judge=0;
+					break;
+				}
+			}
+			if(judge)
+			{
+				new_information[j]=information[i];
+				j++;//最后会有j个被选入 
+			}
+		 } //筛选出了所有学生
+		 
+		 //排序 
+		Sort(new_information,0,j-1);
+		output(new_information,0,j-1);
+	}
+	else if(input==4)
+	{
+		float sum = 0.0;
+		int a = 0;  //a是整数的有几位,也是小数点在字符串的位置
+		for (int i = 0; range[i] != '\0'; i++)
+		{
+		    if (range[i] != '.')
+		    {
+		        a++;
+		    }
+		    else
+		    {
+		        break;
+		    }
+		}
+		//计算sum
+		for (int i = 0; range[i] != '\0'; i++)
+		{
+		    if (i<a)
+		    {
+		        sum += 1.0 * pow10( a - i - 1) * (range[i] - '0');
+		    }
+		    else if(i>a)
+		    {
+		        sum += 1.0 / pow10( i - a) * (range[i] - '0');
+		    }
+		}
+		
+		int j=0;
+		for(int i=0;i<=6;i++)
+		{
+			if(information[i].sum>=sum)
+			{
+				new_information[j]=information[i];
+				j++;//最后会有j个被选入 
+			}
+		 } //筛选出了所有学生
+		 
+		 //排序 
+		Sort(new_information,0,j-1);
+		output(new_information,0,j-1);
+	}
+	else if(input==5)
+	{
+		int classes=10*(range[0]-'0')+(range[1]-'0');
+		int start=10000*(range[3]-'0')+1000*(range[4]-'0')\
+		+100*(range[5]-'0')+10*(range[6]-'0')+(range[7]-'0');;
+		int end=10000*(range[9]-'0')+1000*(range[10]-'0')\
+		+100*(range[11]-'0')+10*(range[12]-'0')+(range[13]-'0');;
+		
+		int j=0;
+		for(int i=0;i<=6;i++)
+		{
+			if(information[i].classes==classes&&\
+			information[i].ID<=end&&information[i].ID>=start)
+			{
+				new_information[j]=information[i];
+				j++;//最后会有j个被选入 
+			}
+		 } //筛选出了所有学生
+		 
+		 //排序 
+		Sort(new_information,0,j-1);
+		output(new_information,0,j-1);
+	}
+	else
+	{
+		printf("请用正确的格式输入查询\n");
+	}	
+}
+
+