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 worldwith logic so firmly plantedcannot discern \n the needs of lovenor comprehend passion from intuitionand requires an explanation\n\t\twhere there is none."""print ("-----------------------")print (poem)print ("-----------------------")five = 10 - 2 + 3 - 6print ("This should be five : %s " % five)def secret_formula(started):jelly_beans = started * 500jars = jelly_beans / 1000crates = jars / 100return jelly_beans , jars , cratesstart_point = 10000beans , 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 / 10print ("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.pyLet's practice everything.You'd need to know 'bout escapes with \ that do  newlines and  tabs.--------------The lovely worldwith logic so firmly plantedcannot discern  the needs of lovenor comprehend passion from intuitionand requires an explanationwhere there is none.--------------This should be five: 5With a starting point of: 10000We'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。