void sort()
{
	FILE *fp;
	struct addritem t;
	int i,j,count=0;
	if((fp=fopen("data.txt","r+"))==NULL)
	{
		printf("can not open\n");
		return;
	}
	while(!feof(fp))
	if(fread(&addrinfo[count],LEN,1,fp)==1)
	count++;
	fclose(fp);
	if(count==0)
	{
		printf("no record!\n");
		return;
	}
	for(i=0;i<count-1;i++)
	for(j=i+1;j<count;j++)
	 if(strcmp(addrinfo[i].name,addrinfo[j].name)>0)
	 {
	 	t=addrinfo[i];
	 	addrinfo[i]=addrinfo[j];
	 	addrinfo[j]=t;
	 }
	 if((fp=fopen("data.txt","w"))==NULL)
	{
		printf("can not open\n");
		return;
	}
	for(i=0;i<count;i++)
	if(fwrite(&addrinfo[i],LEN,1,fp)!=1)
	{
		printf("can not save!\n");
		getch();
	}
	fclose(fp);
	printf("successfully!\n");
}