笨方法学Python 习题 24: 更多练习

#!usr/bin/python
# -*-coding:utf-8-*-

print ("Let's practice everything.")
print ("You\'d need to know \'bout escape 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\twhere there is none.
"""

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)

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))

运行结果如下：

$ python ex24.py
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 there 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.
$

加分习题

①记得仔细检查结果，从后往前倒着检查，把代码朗读出来，在不清楚的位置加上注释。

②故意把代码改错，运行并检查会发生什么样的错误，并且确认你有能力改正这些错误。

常见问题回答

为什么你在后面把 jelly_beans 这个变量名又叫成了 beans ?

这是函数的工作原理。记住函数内部的变量都是临时的，当你的函数返回以后，返回值可以被赋予一个变量。我这里是创建了一个新变量，用来存放函数的返回值。

倒着阅读代码是什么意思?

从最后一行开始，把你写的和我写的代码进行比较。如果这一行完全一样，就接着比较上一行，直到全部比较完为止。

这首诗是谁写的?

我写的。我的诗作偶尔也不赖吧。