python学习笔记（12）布尔运算，if及嵌套，elif，else

1、布尔运算内容

术语	含义
and	与
or	或
not	非
!=	不等于
==	等于
>=	大于等于
<=	小于等于
TRUE	真
FALSE	假

术语	逻辑	值
not	not false	TRUE
	not true	FALSE
or	true or false	TRUE
	true or true	TRUE
	false or true	TRUE
	false or false	FALSE
and	true and false	FALSE
	true and true	TRUE
	false and true	FALSE
	false and false	FALSE
not or	not (true or false)	FALSE
	not (true or true)	FALSE
	not (false or true)	FALSE
	not (false or false)	TRUE
not and	not (true and false)	TRUE
	not (true and true)	FALSE
	not (false and true)	TRUE
	not (false and false)	TRUE
!=	1 != 0	TRUE
	1 != 1	FALSE
	0 != 1	TRUE
	0!= 0	FALSE
==	1 == 0	FALSE
	1 == 1	TRUE
	0 == 1	FALSE
	0 == 0	TRUE

2、if及嵌套

#if语句内部再放入if语句，这是一个很强大的功能，可以用来创建嵌套的决定
#其中一个分支将引向另一个分支的子分支
#多个if...else 里面，python需要检查每个if...else的真假，
#一个if里多个elif ...else里面，python只需要检查到第一个True就可以停下来

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 agiant bear here eating a cheese cake."
          "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("Well,doing %s is probably better."
              "Bear runs away." % bear)

elif door == "2":
    print("You atare 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. Good job!")
    else:
        print("The insanity rots your eyes into a pool of muck. Good job!")

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

#判断一个数处于某个值域中，有2种办法
#1.用经典语法：1 < x < 10
#2.用 x in range(1,10)

#如果多个elif语句为真，python也只会运行第一个为真的elif语句