我有一项家庭作业，我只完成了最低限度的作业，但在完成作业时，我对如何改进我的程序产生了兴趣。代码的要点是绘制用户定义的形状并在输入无效输入时提供反馈。我想继续这样做，如果用户输入 str 作为高度/宽度或其中一个坐标，它会给出错误，但我无法弄清楚该怎么做。这是一个入门类(class)，所以如果您记住我们只是开始 while 循环，我们已经了解了 for 循环，if/else/etc。
这是我目前拥有的代码:
def draw_user_shape(pen):
shape = input("Please enter a shape: ")
while shape != "square" and shape != "rectangle" and shape != "triangle":
shape = input("Invalid shape, please enter either square, rectangle, or triangle: ")
if shape == "square":
h = input("Please enter a height: ")
while h != int or int(h) < 1:
h = input("That is an invalid height, please enter an positive integer: ")
h = int(h)
c = input("Please enter a color: ")
while c != str and str(c) != "red" and str(c) != "green" and str(c) != "blue":
c = input("That is an invalid color, please enter either red, blue, or green: ")
c = str(c)
x = input("Please enter an x-coordinate: ")
while x != int and int(x) == 1:
x = input("That is an invalid x-coordinate, please enter an integer: ")
x = int(x)
y = input("Please enter a y-coordinate: ")
while y != int and int(y) == int:
y = input("That is an invalid y-coordinate, please enter an integer: ")
y = int(y)
pen.fillcolor(c)
pen.up()
pen.goto(x,y)
pen.down()
pen.begin_fill()
pen.goto(x,y+h)
pen.goto(x+h,y+h)
pen.goto(x+h,y)
pen.goto(x,y)
pen.end_fill()
pen.up()
elif shape == "rectangle":
h = input("Please enter a height: ")
while h != int and int(h) < 1:
h = input("That is an invalid height, please enter an positive integer: ")
h = int(h)
w = input("Please enter a width: ")
while w != int and int(w) < 1:
w = input("That is an invalid height, please enter an positive integer: ")
w = int(w)
c = input("Please enter a color: ")
while c != str and str(c) != "red" and str(c) != "green" and str(c) != "blue":
c = input("That is an invalid color, please enter either red, blue, or green: ")
c = str(c)
x = input("Please enter an x-coordinate: ")
while x != int and int(x) == 1:
x = input("That is an invalid x-coordinate, please enter an integer: ")
x = int(x)
y = input("Please enter a y-coordinate: ")
while y != int and int(y) == int:
y = input("That is an invalid y-coordinate, please enter an integer: ")
y = int(y)
pen.fillcolor(c)
pen.up()
pen.goto(x, y)
pen.down()
pen.begin_fill()
pen.goto(x,y+h)
pen.goto(x+w,y+h)
pen.goto(x+w,y)
pen.goto(x,y)
pen.end_fill()
pen.up()
elif shape == "triangle":
h = input("Please enter a height: ")
while h != int and int(h) < 1:
h = input("That is an invalid height, please enter an positive integer: ")
h = int(h)
w = input("Please enter a width: ")
while w != int and int(w) < 1:
w = input("That is an invalid height, please enter an positive integer: ")
w = int(w)
c = input("Please enter a color: ")
while c != str and str(c) != "red" and str(c) != "green" and str(c) != "blue":
c = input("That is an invalid color, please enter either red, blue, or green: ")
c = str(c)
x = input("Please enter an x-coordinate: ")
while x != int and int(x) == 1:
x = input("That is an invalid x-coordinate, please enter an integer: ")
x = int(x)
y = input("Please enter a y-coordinate: ")
while y != int and int(y) == int:
y = input("That is an invalid y-coordinate, please enter an integer: ")
y = int(y)
pen.fillcolor(c)
pen.up()
pen.goto(x,y)
pen.down()
pen.begin_fill()
pen.goto(x+w/2,y+h)
pen.goto(x+w,y)
pen.goto(x,y)
pen.end_fill()
pen.up()
def main():
import turtle
pen = turtle.Turtle()
draw_user_shape(pen)
main()
请您参考如下方法:
在这种情况下，您会希望使用异常处理。基本上，想法是获取输入并尝试 转换为int。如果失败，则会引发 ValueError。否则您将取回转换后的值。请记住，输入将始终作为 str 提供给您，因此您不能简单地测试它是否是 int。假设你使用的是 Python 3，你可以做这样的事情来不断询问，直到输入正确的值:
# keep asking for input until we get the right one
while True:
myInput = input('give me a number: ')
try:
myValue = int(myInput)
# if we reach this point, that means we got our number
break # this will jump out of the loop
except ValueError:
# if we reach this point, that means the input was bad
print('invalid input')
