Why does my program stop responding and crashing? - python-3.x

Question

I was just trying to learn some PyGame which will be needed for my coming project so I would like to know why this sample piece of code is crashing and how I can fix it.
I've tried looking online and haven't found a working solution.
import pygame
# Initialise pygame
pygame.init()
clock = pygame.time.Clock()
# pygame.font.init()
myFont = pygame.font.SysFont('Comic Sans MS', 30)
# Colours
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
BLUE = (0, 0, 255)
GREEN = (0, 255, 0)
RED = (255, 0, 0)
# Screen Size
size = [400, 300]
screen = pygame.display.set_mode(size)
# Initialise Variables
done = False
class Unit:
def __init__(self, name, hp, attack):
self.name = name
self.hp = hp
self.attack = attack
class Infantry(Unit):
def __init__(self, name, hp, attack):
super().__init__(name, hp, attack)
def attack_turn(self):
self.hp -= self.attack
text_surface = myFont.render(self.name + " has " + str(self.hp) + " health points left!", True, (255, 0, 0))
screen.blit(text_surface, (0, 0))
# print(self.name + " has " + str(self.hp) + " health points left!")
x = input("Press ENTER to continue!")
player = Infantry("Panzer", 110, 13) # The attack set here is for the enemy.
enemy = Infantry("T-14", 100, 30) # The attack set here is for the player.
while not done:
for event in pygame.event.get():
if event.type == pygame.QUIT:
done = True
while player.hp > 0 and enemy.hp > 0:
player.attack_turn()
enemy.attack_turn()
done = True
if player.hp > enemy.hp:
# print(player.name + " wins!")
text_surface = myFont.render(player.name + " wins!", False, (255, 0, 0))
screen.blit(text_surface, (100, 100))
else:
# print(enemy.name + " wins!")
text_surface = myFont.render(enemy.name + " wins!", False, (255, 0, 0))
screen.blit(text_surface, (100, 100))
I hoped that the code would at least run so I could work off there but it's not even doing that.

Answer 1

Don't do another loop inside the main loop. The inner loop prevents the event handling, get rid of it. It is sufficient to check if the game has finished at the end of the main loop:
done = False
while not done:
for event in pygame.event.get():
if event.type == pygame.QUIT:
done = True
player.attack_turn()
enemy.attack_turn()
if player.hp <= 0 or enemy.hp <= 0:
done = True
pygame.display.flip()
input does not do what you want it is not an input to the game window. Delete it and sperate the attack method to on method which calculates the new health and a ne method draw, which "blit" the text:
class Infantry(Unit):
def __init__(self, name, hp, attack):
super().__init__(name, hp, attack)
def attack_turn(self):
self.hp -= self.attack
### x = input("Press ENTER to continue!") <----- delete
def draw(self):
text_surface = myFont.render(self.name + " has " + str(self.hp) + " health points left!", True, (255, 0, 0))
screen.blit(text_surface, (0, 0))
Use the pygame.KEYUP event to check if the pygame.K_RETURN key was pressed.
Further do the all the drawing at the end of the main loop. Use pygame.Surface.fill to fill screen by a single color (clear the screen). Then draw the text. Finally use pygame.display.flip() to update the full display:
e.g.
done = False
count = 0
while not done:
attack = False
for event in pygame.event.get():
if event.type == pygame.QUIT:
done = True
elif event.type == pygame.KEYDOWN:
if event.key == pygame.K_RETURN:
attack = True
if attack:
if count % 2 == 0:
player.attack_turn()
else:
enemy.attack_turn()
count += 1
if player.hp <= 0 or enemy.hp <= 0:
done = True
screen.fill(BLACK)
if count % 2 == 0:
player.draw()
else:
enemy.draw()
pygame.display.flip()