习题 27: 记住逻辑关系
and 与
or 或
not 非
!= (not equal) 不等于
== (equal) 等于
>= (greater-than-equal) 大于等于
<= (less-than-equal) 小于等于
True 真
False 假
习题 28:布尔表达式练习
print(True and True)
print(False and True)
print(1==1and2==1)
print("test"=="test")
print(1==1or2!=1)
print(True and1==1)
print(False and0!=0)
print(True or1==1)
print("test"=="testing")
print(1!=0and2==1)
print("test"!="testing")
print("test"==1)
print(not(True and False))
print(not(1==1and0!=1))
print(not(10==1or1000==1000))#False
print(not(1!=10or3==4))#False
print(not("testing"=="testing"and"Zed"=="Cool Guy"))
print(1==1and not("testing"==1or1==0))
print("chunky"=="bacon"and not(3==4or3==3))
print(3==3and not("testing"=="testing"or"Python"=="Fun"))#False
习题 29: 如果(if)
people =20
cats =30
dogs=15
ifpeople < cats:
print("Too many cats! The world is doomed!")
ifpeople > cats:
print("Not many cats! The world is saved!")
ifpeople
print("The world is drooled on!")
ifpeople >dogs:
print("The world is dry!")
dogs+=5
ifpeople >=dogs:
print("People are greater than or equal to dogs.")
ifpeople <=dogs:
print("People are less than or equal to dogs.")
ifpeople ==dogs:
print("People are dogs.")
习题 30: Else 和 If
people =30
cars =40
buses =15
ifcars > people:
print("We should take the cars.")
elifcars < people:
print("We should not take the cars.")
else:
print("We can't decide.")
ifbuses > cars:
print("That's too many buses.")
elifbuses < cars:
print("Maybe we could take the buses.")
else:
print("We still can't decide.")
ifpeople > buses:
print("Alright, let's just take the buses.")
else:
print("Fine, let's stay home then.")
习题 31: 作出决定
print("You enter a dark room with two doors. Do you go through door #1 or door #2?")
door =input("> ")
ifdoor =="1":
print("There's a giant bear here eating a cheese cake. What do you do?")
print("1.Take the cake.")
print("2.Scream at the bear.")
bear =input("> ")
ifbear =="1":
print("The bear eats your face off. Good job!")
elifbear =="2":
print("The bear eats your legs off. Good job.")
else:
print("Well, doing %s is probably better. Bear runs away."% bear)
elifdoor =="2":
print("You stare into the endless abyss at Cthulhu'sretina.")
print("1. Blueberries.")
print("2. Yellow jacket clothespins.")
print("3. Understanding revolvers yelling melodies.")
insanity =input("> ")
ifinsanity =="1"orinsanity =="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!")
习题 32: 循环和列表
the_count = [1,2,3,4,5]
fruits = ["apples","oranges","pears","apricots"]
change = [1,"pennies",2,"dimes",3,"quarters"]
# this first kind of for-loop goes through a list
fornumberinthe_count:
print("This is count %d"% number)
# same as above
forfruitinfruits:
print("A fruit of type: %s"% fruit)
# also we can go through mixed lists too
# notice we have to use %r since we don't know what's in it
foriinchange:
print("I got %r"% i)
# we can also build lists, first start with an empty one
elements = []
# then use the range function to do 0 to 5 counts
foriinrange(0,6):
print("Adding %d to the list."% i)
# append is a function that lists understand
elements.append(i)
# now we can print them out too
foriinelements:
print("Element was: %d"% i)
习题 33: While循环
i =0
numbers = []
whilei <6:
print("At the top i is %d"% i)
numbers.append(i)
i = i +1
print("Numbers now: ",numbers)
print("At the bottom i is %d"% i)
print("The numbers:")
fornuminnumbers:
print(num)
习题 34: 访问列表的元素
animals = ['bear','python','peacock','kangaroo','whale','platypus']
print(animals[0])
print(animals[1])
print(animals[2])
print(animals[3])
print(animals[4])
print(animals[5])
