练习31--做决定

一 if语句的嵌套

1 在嵌套的 if 语句结构，可以在一个 if... elif... else 结构里面可有另外一个 if... elif... else 结构。

语法：

if expression1:
  statement(s)
  if expression2:
   statement(s)
  elif expression3:
   statement(s)
  else
   statement(s)
elif expression4:
  statement(s)
else:
  statement(s)

if、elif、else可组成一个整体的条件语句，其中：

• if是必须有的；
• elif可以没有，也可以有很多个，每个elif的条件不满足时会进入下一个elif的判断；
• else可以没有，有的话只能有一个，必须在条件语句的最后，且没有逻辑判断语句。

二 代码及运行结果

1 ex31.py

print("""You enter a dark room with two doors.
Do you go through door #1 or door #2?""")

door = input(">")

if door == "1":
    print("There's a giant bear here eating a cheese cake.")
    print("What do you do?")
    print("1. Take the cake.")
    print("2. Scream at the bear.")
    
    bear = input(">")
    
    if bear == "1":
        print("The bear eats your face off.Good job!")
    elif bear == "2":
        print("The bear eats your legs off.Good job!")
    else:
        print(f"Well,doing {bear} is probably better.")
        print("Bear runs away.")

elif door == "2":
    print("You stare into the endless abyss at Cthulhu's retina.")
    print("1.Blueberries.")
    print("2.Yellow jacket clothespins.")
    print("3.Understanding revolvers yelling melodies.")
    
    insanity = input(">")
    
    if insanity == "1" or insanity == "2":
        print("Your body survives powered by a mind of jello.")
        print("Good job!")
    else:
        print("The insanity rots your eyes into a pool of muck.")
        print("Good job!")

else:
    print("You stumble around and fall on a knife and die.Good job!")

2 执行结果

PS E:3_work4_python2_code_python2_LearnPythonTheHardWay> python ex31.py
You enter a dark room with two doors.
Do you go through door #1 or door #2?
>2
You stare into the endless abyss at Cthulhu's retina.
1.Blueberries.
2.Yellow jacket clothespins.
3.Underftanding revolvers yelling melodies.
>4
The insanity rots your eyes into a pool of muck.
Good job!