# 2 圣诞树黑白版本

``````def demo1():
height = 5
stars = 1
for i in range(height):
print((' ' * (height - i)) + ('*' * stars))
stars += 2
print((' ' * height) + '|')

if __name__ == "__main__":
demo1()
``````

# 3 海龟绘图

turtle包本身是一个绘图库，但是配合Python代码，就可以绘制各种复杂的图形。

``````# 导入turtle包的所有内容:
from turtle import *
# 设置笔刷宽度:
width(4)
# 前进:
forward(200)
# 右转90度:
right(90)
# 笔刷颜色:
pencolor('red')
forward(100)
right(90)
pencolor('green')
forward(200)
right(90)
pencolor('blue')
forward(100)
right(90)
# 调用done()使得窗口等待被关闭，否则将立刻关闭窗口:
done()
``````

# 4 圣诞树彩色版本

``````
def demo2():
screen = turtle.Screen()
screen.setup(375, 700)
circle = turtle.Turtle()
circle.shape('circle')
circle.color('red')
circle.speed('fastest')
circle.up()

square = turtle.Turtle()
square.shape('square')
square.color('green')
square.speed('fastest')
square.up()

circle.goto(0, 280)
circle.stamp()

k = 0
for i in range(1, 13):
y = 30 * i
for j in range(i - k):
x = 30 * j
square.goto(x, -y + 280)
square.stamp()
square.goto(-x, -y + 280)
square.stamp()

if i % 4 == 0:
x = 30 * (j + 1)
circle.color('red')
circle.goto(-x, -y + 280)
circle.stamp()
circle.goto(x, -y + 280)
circle.stamp()
k += 3

if i % 4 == 3:
x = 30 * (j + 1)
circle.color('yellow')
circle.goto(-x, -y + 280)
circle.stamp()
circle.goto(x, -y + 280)
circle.stamp()

square.color('brown')
for i in range(13, 17):
y = 30 * i
for j in range(2):
x = 30 * j
square.goto(x, -y + 280)
square.stamp()
square.goto(-x, -y + 280)
square.stamp()

turtle.done()
``````

THE END