《笨办法学Python》习题24、25

习题24：更多的练习

这次练习将前面学习的主要内容都有进行了练习和展示

print("Let's practice everything.")
print('You\'d need to know \' bout escapes with \\ that do \n newlines and \t tabs.')

poem =( """
\tThe lovely world
with logic so firmly planted
cannot discern \n the needs of love
nor comprehend passion from intuition
and requires an explanation
\n\t\t\twhere is none.
""")
#从制表符里面可以知道\t，会出现8个空格
print("-----------------")
print(poem)
print("-----------------")

five = 10 - 2 + 3 - 6
print("This should be five:%s"%five)

def secret_formula(started):
    jelly_beans = started*500
    jars = jelly_beans / 1000
    crates = jars / 100
    return (jelly_beans,jars,crates)

start_point = 10000
beans,jars,crates = secret_formula(start_point)
#将secret_formula返回得到的三个值分别赋值给beans、jars、crates，外面的变量才是持久的，而函数内部的变量是可变的、临时的
print("With a starting point of:%d"%start_point)
print("We'd have %d beans,%d jars, and %d crates."%(beans,jars,crates))

start_point = start_point / 10

print("We can also do that this way:")
print("We'd have %d beans,%d jars,and %d crates."%secret_formula(start_point))
#将函数中的三个值分别给了前面，这样子省去了设置新变量进行赋值的过程

结果：

Let's practice everything.
You'd need to know ' bout escapes with \ that do
 newlines and    tabs.
-----------------

        The lovely world
with logic so firmly planted
cannot discern
 the needs of love
nor comprehend passion from intuition
and requires an explanation

                        where is none.

-----------------
This should be five:5
With a starting point of:10000
We'd have 5000000 beans,5000 jars, and 50 crates.
We can also do that this way:
We'd have 500000 beans,500 jars,and 5 crates.

习题25：更多更多的练习

def break_words(stuff):
   """This function will break up words for us."""#充当帮助文档
   words = stuff.split(' ')#split用于切片
   return(words)
   
def sort_words(words):
   """Sorts the words"""
   return(sorted(words))
#sorted() 作为 Python 内置函数之一，其功能是对序列（列表、元组、字典、集合、还包括字符串）进行排序
#基本语法为：list = sorted(iterable, key=None, reverse=False)
   
def print_first_word(words):
   """Prints the last word after popping it off."""
   word = words.pop(0)
   print(word)
#pop() 函数用于移除列表中的一个元素（默认最后一个元素），并且返回该元素的值
#语法：list.pop(obj=list[-1])       //默认为 index=-1，删除最后一个列表值
def print_last_word(words):
   """Prints the last word after popping it off."""
   word = words.pop(-1)
   print(word)
   
def sort_sentence(sentence):
   """Takes in a full sentence and returns the sorted words."""
   words = break_words(sentence)
   return(sort_words(words))
#函数之中套用函数，由于此处用法一致，故而得出结果一致
def print_first_and_last(sentence):
   """Prints the first and last words of the sentence"""
   words = break_words(sentence)
   print_first_word(words)
   print_last_word(words)
#函数之中套用多个函数，返回前值
def print_first_and_last_sorted(sentence):
   """Sorts the words then prints the first and last one."""
   words = sort_sentence(sentence)
   print_first_word(words)
   print_last_word(words)
#返回有序的列表的前后值

结果为:

>>> sentence = "All good things come to those who wait."
>>> words = pra25.break_words(sentence)
>>> words
['All', 'good', 'things', 'come', 'to', 'those', 'who', 'wait.']
>>> sorted_words = pra25.sort_words(words)
>>> sorted_words
['All', 'come', 'good', 'things', 'those', 'to', 'wait.', 'who']
>>> pra25.print_first_word(words)
All
>>> pra25.print_last_word(words)
wait.
>>> words
['good', 'things', 'come', 'to', 'those', 'who']
>>> pra25.print_first_word(sorted_words)
All
>>> pra25.print_last_word(sorted_words)
who
>>> sorted_words
['come', 'good', 'things', 'those', 'to', 'wait.']
>>> sorted_words = pra25.sort_sentence(sentence)
>>> sorted_words
['All', 'come', 'good', 'things', 'those', 'to', 'wait.', 'who']
>>> pra25.print_first_and_last(sentence)
All
wait.
>>> pra25.print_first_and_last_sorted(sentence)
All
who