未定义Python名称“height”

Question

我有一个计算机科学作业，我需要写一个函数main()，它调用一个函数drawChessboard()来绘制一个8x8的棋盘，在那里用户可以确定棋盘的宽度和高度。我们正在学习函数和模块，我们需要使用多个具有多个函数的模块。这是我的第一个模块：

from chessboard import *

def main():

    startX, startY = eval(input("Enter the starting coordinates (x, y): "))
    width = input("Enter the width: ")
    height = input("Enter the height: ")
    spaceX = eval(width) / 8
    spaceY = eval(height) / 8

    def variables():
        global startX, startY, width, height, spaceX, spaceY, xLocation, yLocation

    if width == "" and height == "":
        drawChessboard(startX, startY)
    elif height == "":
        drawChessboard(startX, startY, width=eval(width))
    elif width == "":
        drawChessboard(startX, startY, height=eval(height))
    else:
        drawChessboard(startX, startY, eval(width), eval(height))


main()

这是第二个模块，名为：棋盘.py在

^{pr2}$

当第一个的语句时，它给出了一个错误 未定义名称height。 我不知道怎么解决这个问题。我试着把所有变量都设为全局变量，但结果还是一样。我在这个网站上查到了这个错误，但是我没有运气。我做错什么了吗？在

Answer 1

你在这个函数中使用了两次高度

def drawAllRectangles(startX, startY):          # function that will draw all rectangles to make up chessboard

    yLocation = startY
    while yLocation <= (height - 2 * spaceY):   # draw rectangles on rows 1, 3, 5, 7
        global xLocation
        xLocation = startX
        while xLocation <= (width - 2 * spaceX):
            drawRectangle()
            xLocation += 2 * spaceX
        yLocation += 2 * spaceY

    turtle.penup()
    turtle.goto(startX + spaceX, startY + spaceY)
    turtle.pendown()
    yLocation = startY + spaceY
    while yLocation <= (height - spaceY):       # draw rectangles on rows 2, 4, 6, 8
        xLocation = startX + spaceX
        while xLocation <= (width - spaceX):
            drawRectangle()
            xLocation += 2 * spaceX
        yLocation += 2 * spaceY

该函数中不存在该变量。不要使用global。你用身高

^{pr2}$

所以你需要在这里做同样的事情

def drawAllRectangles(startX, startY, width, height): 

所以当你调用drawAllRectangles时，确保你传入了这4个变量。在

另外，将所有导入移到文件的顶部。看看eval做了什么（https://www.programiz.com/python-programming/methods/built-in/eval）。你不需要在你的程序中的任何地方都需要全局数据或评估。在

Answer 2

When I remove global, all the variables aren't defined for use and I get errors. What can I do for that?

我同意@anon（+1）关于全局变量和代码中的eval()的观点。下面是我对你的代码san全局变量的重新设计，你应该能够根据需要把它分成两个单独的文件。您需要（重新）阅读global关键字的作用和使用位置。我知道eval()在输入元组时很方便，但是您应该找到另一种方法。我将其他eval()调用替换为int()：

import turtle

def drawRectangle(xLocation, yLocation, spaceX, spaceY):

    turtle.penup()
    turtle.goto(xLocation, yLocation)
    turtle.pendown()

    turtle.begin_fill()

    for _ in range(2):
        turtle.forward(spaceX)
        turtle.left(90)
        turtle.forward(spaceY)
        turtle.left(90)

    turtle.end_fill()

def drawAllRectangles(startX, startY, width, height):
    """ Draw all rectangles to make up chessboard """

    spaceX = width / 8
    spaceY = height / 8

    yLocation = startY

    while yLocation <= (height - 2 * spaceY):  # draw rectangles on rows 1, 3, 5, 7
        xLocation = startX
        while xLocation <= (width - 2 * spaceX):
            drawRectangle(xLocation, yLocation, spaceX, spaceY)
            xLocation += 2 * spaceX
        yLocation += 2 * spaceY

    turtle.penup()
    turtle.goto(startX + spaceX, startY + spaceY)
    turtle.pendown()

    yLocation = startY + spaceY

    while yLocation <= (height - spaceY):  # draw rectangles on rows 2, 4, 6, 8
        xLocation = startX + spaceX
        while xLocation <= (width - spaceX):
            drawRectangle(xLocation, yLocation, spaceX, spaceY)
            xLocation += 2 * spaceX
        yLocation += 2 * spaceY

def drawChessboard(startX, startY, width=250, height=250):

    """ Draw outside border for chessboard """

    turtle.penup()
    turtle.goto(startX, startY)
    turtle.pendown()

    for _ in range(2):
        turtle.forward(width)
        turtle.left(90)
        turtle.forward(height)
        turtle.left(90)

    drawAllRectangles(startX, startY, width, height)

def main():

    startX, startY = eval(input("Enter the starting coordinates (x, y): "))
    width = input("Enter the width: ")
    height = input("Enter the height: ")

    turtle.speed('fastest')

    if width == "" and height == "":
        drawChessboard(startX, startY)
    elif height == "":
        drawChessboard(startX, startY, width=int(width))
    elif width == "":
        drawChessboard(startX, startY, height=int(height))
    else:
        drawChessboard(startX, startY, int(width), int(height))

    turtle.done()

main()

用pythonthurtle绘制棋盘并不需要太多代码和精力。我建议您研究一下stamp()，这样既可以加快速度又可以简化它。在