按C重新加载/重新执行代码时出错？

Question

我试图用TheNewBoston的教程制作一个蛇游戏，因为我是一名中学生，在Python方面没有太多经验。代码是：

__author__ = 'Ded'

import pygame
import time

pygame.init()

display_width = 800
display_height = 600


gameDisplay = pygame.display.set_mode((display_width, display_height))

pygame.display.set_caption('Dipshit')

white = (255, 255, 255)
black = (0, 0, 0)
red = (255, 0, 0)
green = (0, 255, 0)
blue = (0, 0, 255)

clock = pygame.time.Clock()

block_size = 10
FPS = 30

font = pygame.font.SysFont(None, 25)

def message_to_screen(msg,color):
    screen_text = font.render(msg, True, color)
    gameDisplay.blit(screen_text, [display_width/2, display_height/2])


def gameLoop():
    gameExit = False
    gameOver = False

    lead_x = display_width/2
    lead_y = display_height/2
    lead_x_change = 0
    lead_y_change = 0

    while not gameExit:

        while gameOver == True:
            gameDisplay.fill(white)
            message_to_screen("Game over, press C to play again or Q to quit", red)
            pygame.display.update()

            for event in pygame.event.get():
                if event.type == pygame.KEYDOWN:
                    if event.key == pygame.K_q:
                        gameExit = True
                        gameOver = False
                    if event.key == pygame.K_c:
                        gameLoop()

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                gameExit = True
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_LEFT:
                    lead_x_change -= block_size
                    lead_y_change = 0
                if event.key == pygame.K_RIGHT:
                    lead_x_change += block_size
                    lead_y_change = 0
                if event.key == pygame.K_DOWN:
                    lead_y_change += block_size
                    lead_x_change = 0
                if event.key == pygame.K_UP:
                    lead_y_change -= block_size
                    lead_x_change = 0


        if event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
                lead_x_change = 0

        if event.type == pygame.KEYUP:
            if event.key == pygame.K_DOWN or event.key == pygame.K_UP:
                lead_y_change = 0

        if lead_x >= display_width or lead_x < 0 or lead_y >= display_height or lead_y < 0:
            gameOver = True

        lead_x += lead_x_change
        lead_y += lead_y_change

        gameDisplay.fill(white)
        pygame.draw.rect(gameDisplay, black, [lead_x,lead_y,block_size,block_size])


        pygame.display.update()

        clock.tick(FPS)
    pygame.quit()
    quit()

gameLoop()

但是，当我执行、播放、丢失并按C重试时，会出现此错误。当我想退出时，Q可以正常工作，但C只是退出，并打印此错误：

C:\Python34\python。exe“C:/Users/Ded/PycharmProjects/PyGame/PyGame Tutorial.py”回溯（上次调用）：文件“C:/Users/Ded/PycharmProjects/PyGame/PyGame Tutorial.py”，第100行，在gameLoop（）文件“C:/Users/Ded/PycharmProjects/PyGame/PyGame Tutorial.py”第56行，在gameLoop（）文件“C:/Users/Ded/PycharmProjects/PyGame/PyGame Tutorial.PyGame”第76行，在gameLoop if事件中。type==pygame。KEYUP:UnboundLocalError:赋值前引用的局部变量“event”

退出代码1的过程结束

Answer 1

您需要缩进代码的以下部分：

    if event.type == pygame.KEYUP:
        if event.key == pygame.K_LEFT or event.key == pygame.K_RIGHT:
            lead_x_change = 0

    if event.type == pygame.KEYUP:
        if event.key == pygame.K_DOWN or event.key == pygame.K_UP:
            lead_y_change = 0

因此，它们是for循环的一部分。否则，如果没有要获取的事件，也没有循环的迭代发生，变量事件将不会被定义。