循环打印变量值延迟一次迭代

Question

我正在使用 Learn Python The Hard Way 学习编程。在练习 43 的学习训练中，作者希望我们构建一个简单的战斗系统，用于英雄遇到敌人时。

在我的战斗系统中，玩家和敌人都以 100 HP 开始。我设置了一个列表，其中包含 4 个随机提示玩家。根据提示，玩家需要做出反应。根据场景和反应，玩家会损失生命值、对敌人造成伤害或不受影响。每当他们改变时，程序都会打印出玩家和敌人的剩余HP。

health = 100
enemy_health = 100

battle_prompts = [
    "The Gothon raises his rifle, aiming it square in your face.",
    "The Gothon aims, then pauses, realising he's yet to reload his ammo.",
    "The Gothon charges at you at lightspeed, fists clenched tight.",
    "The Gothon runs in your direction, with a menacing grin on his face."
]

while health != 0 and enemy_health != 0:
    battle_prompt = battle_prompts[randint(0,3)]
    print (battle_prompt)
    action = input("> ")
    healthbar = (f"HEALTH: {health} | ENEMY HEALTH: {enemy_health}")
    if battle_prompt == battle_prompts[0] and action == "dodge":
        print ("You dodge the bullet successfully. Nice one!")
    elif battle_prompt == battle_prompts[0] and action != "dodge":
        health -= 25
        print ("You fool! You just got shot!")
        print (healthbar)
    elif battle_prompt == battle_prompts[1] and action == "shoot":
        enemy_health -= 25
        print ("Cool! You just caused some alien bloodshed!")
        print (healthbar)
    elif battle_prompt == battle_prompts[1] and action != "shoot":
        print ("The Gothon reloads his rifle successfully. A wasted opportunity!")
    elif battle_prompt == battle_prompts[2] and action == "block":
        print("You manage to block the Gothon's deadly punches. Way to go!")
    elif battle_prompt == battle_prompts[2] and action != "block":
        health -= 25
        print("What a lamebrain! You just got pounded by an alien!")
        print (healthbar)
    elif battle_prompt == battle_prompts[3] and action == "punch":
        enemy_health -= 25
        print("You give that extraterrestrial invader a beautiful uppercut. Wow!")
        print (healthbar)
    elif battle_prompt == battle_prompts[3] and action != "punch":
        print("The Gothon knocks you over. You're not hurt, but you wasted an opportunity.")
else:
    if health == 0:
        print ("Whoops! Guess you're outta health points! That's all folks!")
        return 'death'
    elif enemy_health == 0:
        print("Good job! You defeated an armed citizen of a galaxy unknown fair and square!")
        return 'escape_pod'

我将剩余的 HP 提示分配给变量 healthbar，但似乎无法使其正常工作。如果 HP 有变化，则不会反映在紧随其后打印的提示中；仅在下次 HP 发生变化时显示。我想你可以说提示总是“延迟”一次循环迭代。

例如： 如果我在第一轮造成 25 点伤害，那么输出是 HEALTH: 100 | ENEMY HEALTH: 100 在第二轮中，敌人造成 25 点伤害。输出： HEALTH: 100 | ENEMY HEALTH: 75 如果我在第三轮躲避攻击，输出是： HEALTH: 75 | ENEMY HEALTH: 75

程序“实时”计算 HP 值，即如果任何角色的 HP 为零，则执行 while 循环的 else 块，但提示仍然显示他们还剩 25HP。

我尝试将 healthbar 移到 while 循环之外，但提示显示 HP 值始终为 100。但是，当我完全取消 healthbar 变量并通过粘贴替换它的每个实例时整个提示，一切都正确显示。我做错了什么？

Answer 1

每次操作后，您打印旧 healthbar。然后你进入循环的底部，输入下一个动作，只有然后你才会用上一个动作的结果更新healthbar。

通过将打印与文本分离来解决此问题。在循环底部更新和打印：

当健康！= 0 和敌人健康！= 0： 战斗提示 = 战斗提示 [randint(0,3)] 打印（battle_prompt） 动作=输入（>“）

if battle_prompt == battle_prompts[0] and action == "dodge":
    print ("You dodge the bullet successfully. Nice one!")
elif battle_prompt == battle_prompts[0] and action != "dodge":
    health -= 25
    print ("You fool! You just got shot!")
... all other choices ...

healthbar = (f"HEALTH: {health} | ENEMY HEALTH: {enemy_health}")
print (healthbar)

输出：

The Gothon runs in your direction, with a menacing grin on his face.
> shoot
The Gothon knocks you over. You're not hurt, but you wasted an opportunity.
HEALTH: 100 | ENEMY HEALTH: 100
The Gothon runs in your direction, with a menacing grin on his face.
> punch
You give that extraterrestrial invader a beautiful uppercut. Wow!
HEALTH: 100 | ENEMY HEALTH: 75
The Gothon charges at you at lightspeed, fists clenched tight.
> punch
What a lamebrain! You just got pounded by an alien!
HEALTH: 75 | ENEMY HEALTH: 75

Answer 2

您正在使用旧的健康值格式化healthbar（创建字符串），修改健康值，然后再次打印旧的健康值。

我建议制作一个“可格式化”的字符串模板，并且只在必要时进行格式化。您还可以创建一个功能来打印它。我相信你知道如何为此编写一个函数，所以这里是如何使用格式模板技术：

health = 100
enemy_health = 100

battle_prompts = [
    "The Gothon raises his rifle, aiming it square in your face.",
    "The Gothon aims, then pauses, realising he's yet to reload his ammo.",
    "The Gothon charges at you at lightspeed, fists clenched tight.",
    "The Gothon runs in your direction, with a menacing grin on his face."
]

# Template
healthbar = "HEALTH: {health} | ENEMY HEALTH: {enemy_health}"

while health != 0 and enemy_health != 0:
    battle_prompt = battle_prompts[randint(0,3)]
    print (battle_prompt)
    action = input("> ")
    if battle_prompt == battle_prompts[0] and action == "dodge":
        print ("You dodge the bullet successfully. Nice one!")
    elif battle_prompt == battle_prompts[0] and action != "dodge":
        health -= 25
        print ("You fool! You just got shot!")
        print (healthbar.format(health=health, enemy_health=enemy_health))
    elif battle_prompt == battle_prompts[1] and action == "shoot":
        enemy_health -= 25
        print ("Cool! You just caused some alien bloodshed!")
        print (healthbar.format(health=health, enemy_health=enemy_health))
    elif battle_prompt == battle_prompts[1] and action != "shoot":
        print ("The Gothon reloads his rifle successfully. A wasted opportunity!")
    elif battle_prompt == battle_prompts[2] and action == "block":
        print("You manage to block the Gothon's deadly punches. Way to go!")
    elif battle_prompt == battle_prompts[2] and action != "block":
        health -= 25
        print("What a lamebrain! You just got pounded by an alien!")
        print (healthbar.format(health=health, enemy_health=enemy_health))
    elif battle_prompt == battle_prompts[3] and action == "punch":
        enemy_health -= 25
        print("You give that extraterrestrial invader a beautiful uppercut. Wow!")
        print (healthbar.format(health=health, enemy_health=enemy_health))
    elif battle_prompt == battle_prompts[3] and action != "punch":
        print("The Gothon knocks you over. You're not hurt, but you wasted an opportunity.")
else:
    if health == 0:
        print ("Whoops! Guess you're outta health points! That's all folks!")
        return 'death'
    elif enemy_health == 0:
        print("Good job! You defeated an armed citizen of a galaxy unknown fair and square!")
        return 'escape_pod'