条件、循环、函数定义 练习

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：
   1. 画五角星

      import turtle
      turtle.speed(6)
      for i in range(5):
          turtle.forward(100)
          turtle.right(144)
      turtle.hideturtle()

      

   2. 画同心圆

      import turtle
      for i in range(9):
          turtle.up()
          turtle.goto(0,-20*(i+1))
          turtle.down()
          turtle.circle(20*(i+1))
      turtle.hideturtle()

      

   3. 画太阳花

      import turtle
      turtle.speed(10)
      turtle.color('blue','yellow')
      turtle.begin_fill()
      while True:
          turtle.forward(250)
          turtle.left(170)
      if(abs(turtle.pos()))<1:
      break
      turtle.end_fill()
      done()

      

   4. 画五个五角星

      import turtle
      turtle.speed(10)
      turtle.color('yellow')
      turtle.bgcolor('red')
      
      def mygoto(x,y):
          turtle.up()
          turtle.goto(x,y)
          turtle.down()
      
      def drawfive(r):
          turtle.begin_fill()
      for i in range(5):
               turtle.forward(r)
               turtle.right(144)
          turtle.end_fill()
      #大星
      mygoto(-300,150)
      drawfive(100)
      #小星
      mygoto(-200,230)
      drawfive(50)
      mygoto(-150,170)
      drawfive(50)
      mygoto(-150,100)
      drawfive(50)
      mygoto(-200,50)
      drawfive(50)
      turtle.hideturtle()

      

   5. 画◇花瓣的太阳花

      import turtle
      turtle.speed(10)
      turtle.color("blue")
      turtle.fillcolor('yellow')
      def drawlx():
      for i in range(1,3):
              turtle.forward(100)
              turtle.right(45)
              turtle.forward(100)
              turtle.right(135)
      for i in range(1,40):
          turtle.begin_fill()
          drawlx()
          turtle.right(20)
          turtle.end_fill()
      turtle.right(90)
      turtle.hideturtle()