一、作业内容

作业越拖越多怎么办，跪了 。

二、作业代码

• 习题27：记住逻辑关系

# 习题27：记住逻辑关系
'''
常用逻辑术语：
and 与
or 或
not 非
!= 不等于
== 等于 # 为什么不直接用“=”，是为区别基本的运算，“=”类似于赋值
>= 大于等于
<= 小于等于
True 真
False 假
'''
# Test
print(1==1)
print(True or False)

• 习题28：布尔表达式练习

# 习题28：布尔表达式练习
# Test
print(True and True)
print(False and True)
print(1 == 1 and 2 == 1)
print("test" == "test" )
print(1 == 1 and 2 == 1)
print(3 == 3 and not ("testing" == "testing" or "Python" == "Fun"))
'''
Summary:
作为理科生应对这个还好，两个要点：
1、一步步细致地演算
2、计算先后顺序不乱
计算先后顺序：
1、找到相等判断的部分（== or !=）并将其改写成最终值（True/FAlse）
2、找到括号里的and/or，先算出它们的值
3、找到每一个not，算出它们反过来的值
4、找到剩下的and/or，解出它们的值
5、完成以上步骤，剩下的结果就应该是True/False
'''

• 习题29：如果（if）

# 习题29：如果（if）
people = 20
cats = 30
dogs = 15
if people < cats:
    print("Too many cats! The world is doomed!")
if people > cats:
    print("Not many cats! The world is saved!")
if people < dogs:
    print("The world is drooled on!")
if people > dogs:
    print("The world is dry!")
dogs += 5
if people >= dogs:
    print("People are greater than or equal to dogs.")
if people <= dogs:
    print("People are less than or equal to dogs.")
if people == dogs:
    print("People are dogs.")
'''
Smmary：
1、以前学过C++理解这个条件语句困难不大
2、注意语法格式，会自动缩放真好
'''

• 习题30：Else和If

# 习题30：Else和If
people = 30
cars = 40
buses = 15
if cars > people:
    print("We should take the cars.")
elif cars < people:
    print("We should not take the cars.")
else:
    print("We can't decide.")
if buses > cars:
    print("That's too many buses.")
elif buses < cars:
    print("Maybe we could take the buses.")
else:
    print("We still can't decide.")
if people > buses:
    print("Alright, let's just take the buses.")
else:
    print("Fine,let's stay home then.")
'''
Summary:
1、elif在C++中表述为全称 else if
2、else就是否则
3、elif是在没有穷尽所有条件情况下使用，else就是非if情况
'''

• 习题31：作出决定

# 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(">") # 原文中为raw_input应为版本问题
if door == "1":
    print("These'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(">")
    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 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. 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!")
'''
Summary：
1、此中新的知识点：input、嵌套语句
2、注意input的格式
'''

• 习题32：循环和列表

# 习题32：循环和列表
the_count = [1, 2, 3, 4]
fruits = ['apples', 'oranges', 'pears', 'apricots']
change = [1, 'pennies', 2, 'dimes', 3, 'quarters']
# this first kind of for-loop goes through a list
for number in the_count:
    print("This is count %d" % number)
# same as above
for fruit in fruits:
    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
for i in change:
    print("I got %r" % i)
# we can also build lists, first start with an empty one
elements = [] # 定义了一个空集
# then use the range function to do 0 to 5 counts
for i in range(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
for i in elements:
    print("Element was: %d" % i)
'''
Summary:
1、格式化字符在循环里运用简直绝配
2、for循环C++学过理解起来没有太困难
3、for fruit in fruits: print("A fruit of type: %s" % fruit)这段语句中相当于一个变量赋值，即用fruits集合中的元素去给fruit这一变量赋值，最后输出时读取fruit变量
4、新知识点range(0,6)代表0到6但不包含6也可以写成range(6)，而range(0,6,2)代表0到6间隔2，不包括6，也就是[0,2,4]
5、新知识点append为在列表末尾添加新的对象，该程序中elements.append(i)为在elements[]集合后面添加i，而i=range(0,6)=[0,1,2,3,4,5]，所以最后的输出才会是一个循环，而不是直接输出原额，elements中的空集
'''

• 习题33：While 循环

# 习题33：While 循环
i = 0
numbers = []
while i < 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:")
for num in numbers:
    print(num)
'''
Summary:
1、按照逻辑，会将上面while这个循环模块的循环走完以后才跳出循环模块读接下来的语句
2、 numbers.append(i)
    i=i+1
    print("Numbers now:", numbers)
    这一段虽然i已经等于1，为何输出仍为[0]，因为i=1后并未做一次append运算，也即尚未将1添加进集合
3、while容易死循环，ctrl+C是停止循环的快捷键
4、while有点for和if结合的味道
'''
# 加分习题：用for和range把脚本再写一遍，需要加上if条件语句
numbers_2 = []
for j in range(6):
    if j<6:
        print("At the top j is %d" % j)
        numbers_2.append(j)
        j=j+1
        print("Numbers now:", numbers_2)
        print("At the bottom j is %d" % j)
print("The numbers:")
for num in numbers_2:
    print(num)

• 习题34：访问列表的元素

# 习题34：访问列表的元素
animals = ['bear', 'tiger', 'penguin', 'fish', 'cat', 'dog']
for i in range(0,6):
    j=i+1
    print("The %d animal is:" % j,animals[i])
'''
Summary:
 1、animals[i]提取集合中的第i个元素
 2、从0开始计数
'''

三、学习总结

• 现在感觉抄抄会抄，自己独立不参考任何代码写好像还写不出来，不够熟练
• 继续赶作业吧