diff --git a/6.c b/6.c
new file mode 100644
index 0000000..68459b1
--- /dev/null
+++ b/6.c
@@ -0,0 +1,63 @@
+#include<stdio.h>
+#include<string.h> 
+#define N 3
+
+struct stu_info
+{
+	char num[20];
+	int cls,flag;
+	char name[20];
+	float math,physics,english;
+};
+
+struct stu_info stu[N]={{"10001",11,0,"Zhang",99.5,88.5,89.5},
+						{"10002",12,0,"Yang",77.9,56.5,87.5},
+						{"10003",11,0,"Liang",92.5,99.0,60.5}};
+
+void sort(struct stu_info *stu,int n)
+{
+	int i,j;
+	struct stu_info tmp;
+	for(i=0;i<n;i++)
+	{
+		for(j=0;j<n-i-1;j++)
+		{
+			if(((stu+j)->cls>(stu+j+1)->cls)||((stu+j)->cls==(stu+j+1)->cls)&&((stu+j)->num>(stu+j+1)->num))
+			{
+				tmp = *(stu+j);
+				*(stu+j) = *(stu+j+1);
+				*(stu+j+1) = tmp;
+			} 
+		}
+	}
+	return;
+}
+
+int main()
+{
+	struct stu_info mod;
+	scanf("%s",&mod.num);
+	scanf("%d",&mod.cls);
+	scanf("%s",&mod.name);
+	scanf("%f",&mod.math);
+	scanf("%f",&mod.physics);
+	scanf("%f",&mod.english);
+	int i;
+	for(i=0;i<N;i++)
+	{
+		if(strcmp(stu[i].num,mod.num)==0)
+		{
+			*(stu+i)=mod;
+		}
+	}
+	sort(stu,N);
+	for(i=0;i<N;i++)
+	{
+		if(i==0||stu[i].cls!=stu[i-1].cls) printf("%2d ",stu[i].cls);
+		else printf("   "); 
+		printf("%s %s %.1f %.1f %.1f",stu[i].num,stu[i].name,stu[i].math,stu[i].physics,stu[i].english);
+		if(stu[i].flag) printf(" modified");
+		printf("\n"); 
+	}
+	return 0;
+}