作业4——条件、循环、函数语句

1. 注意标准库的两种导入与使用方式，建议大家采用<库名>.<函数名>的方式。
2. 对前面的代码进行优化，用for,while,if,def实现：

a.画五角星

import turtle
turtle.setup(600,400,0,0)
turtle.color('yellow')
turtle.bgcolor('red')
turtle.fillcolor('yellow')
turtle.up()
turtle.goto(-250,75)
turtle.down()
turtle.begin_fill()
for i in range(5):
    turtle.forward(100)
    turtle.right(144)
turtle.end_fill()

b.画同心圆

import turtle

for i in range(5):
    turtle.up()
    turtle.goto(0,-20*(i+1))
    turtle.down()
    turtle.circle(20*(i+1))
    turtle.write(10-i)

c.画太阳花

from turtle import *

color('red','blue')
begin_fill()
while True:
    forward(100)
    left(170)
    if(abs(pos()))<1:
        break
end_fill()
done()

d.画五个角星

import turtle

turtle.setup(600,400,0,0)
turtle.color('yellow')
turtle.bgcolor('red')
turtle.fillcolor('yellow')

def mygoto(x,y):
    turtle.up()
    turtle.goto(x,y)
    turtle.down()
    
mygoto(-250,75)
turtle.begin_fill()
for i in range(5):
    turtle.forward(100)
    turtle.right(144)
turtle.end_fill()

mygoto(-100,150)
turtle.begin_fill()
for i in range(5):
    turtle.forward(50)
    turtle.right(144)
turtle.end_fill()

mygoto(-80,80)
turtle.begin_fill()
for i in range(5):
    turtle.forward(50)
    turtle.right(144)
turtle.end_fill()

mygoto(-70,20)
turtle.begin_fill()
for i in range(5):
    turtle.forward(50)
    turtle.right(144)
turtle.end_fill()

mygoto(-80,-40)
turtle.begin_fill()
for i in range(5):
    turtle.forward(50)
    turtle.right(144)
turtle.end_fill()