void black(){
digitalWrite(2, HIGH);
digitalWrite(3, HIGH);
digitalWrite(4, HIGH);
digitalWrite(5, HIGH);
digitalWrite(6, HIGH);
digitalWrite(7, HIGH);
digitalWrite(8, HIGH);
}

void setup(){
 pinMode(2,OUTPUT);
 pinMode(3,OUTPUT);
 pinMode(4,OUTPUT);
 pinMode(5,OUTPUT);
 pinMode(6,OUTPUT);
 pinMode(7,OUTPUT);
 pinMode(8,OUTPUT);
}
void loop(){
//清空
black();
//显示9
digitalWrite(2, LOW);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
digitalWrite(5, LOW);
digitalWrite(7, LOW);
digitalWrite(8, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
//显示8
digitalWrite(2, LOW);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
digitalWrite(5, LOW);
digitalWrite(6, LOW);
digitalWrite(7, LOW);
digitalWrite(8, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
//显示7
digitalWrite(2, LOW);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
//显示6
digitalWrite(2, LOW);
digitalWrite(4, LOW);
digitalWrite(5, LOW);
digitalWrite(6, LOW);
digitalWrite(7, LOW);
digitalWrite(8, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
//显示5
digitalWrite(2, LOW);
digitalWrite(4, LOW);
digitalWrite(5, LOW);
digitalWrite(7, LOW);
digitalWrite(8, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
//显示4
digitalWrite(3, LOW);
digitalWrite(4, LOW);
digitalWrite(7, LOW);
digitalWrite(8, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
//显示3
digitalWrite(2, LOW);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
digitalWrite(5, LOW);
digitalWrite(8, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
//显示2
digitalWrite(2, LOW);
digitalWrite(3, LOW);
digitalWrite(5, LOW);
digitalWrite(6, LOW);
digitalWrite(8, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
//显示1
digitalWrite(3, LOW);
digitalWrite(4, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
//显示0
digitalWrite(2, LOW);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
digitalWrite(5, LOW);
digitalWrite(6, LOW);
digitalWrite(7, LOW);
//延时
delay(1000);
//清空
black();
//延时
delay(1000);
}