习题32 循环和列表

首先要知道怎么创建列表

        以左方括号  [    开头，打开列表，然后写下你要放入列表的东西，用逗号隔开，就跟函数的参数一样，最后用右方括号  ]   结束定义。然后Python接收这个列表及里边所有的内容，将其赋给一个变量。

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 gose through a listfor number in the_count:    print "This is count %d" % number    # same as abovefor 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 itfor i in change:    print "I got %r" % i# we can also build lists, first start with an empty oneelements = []# then use the range function to do 0 to 5 countsfor 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 then out toofor i in elements:    print "Element was:%d" % i

运行结果如下

这里面的 for 循环比C++简单

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附加练习

1.  range 函数的 range( )里面应该是填写的范围

>>>range(1,5)#代表从1到5(不包含5)

[1,2,3,4]

>>>range(1,5,2)#代表从1到5，间隔2(不包含5)

[1,3]

>>>range(5)#代表从0到5(不包含5)

[0,1,2,3,4]

这是网上搜的

2.

改动如下

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 gose through a listfor number in the_count:    print "This is count %d" % number    # same as abovefor 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 itfor i in change:    print "I got %r" % i# we can also build lists, first start with an empty oneelements = []# then use the range function to do 0 to 5 countsi in range(0,6)    print "Adding %s to the list." % i# append is a function that lists understand    elements.append(i)    # now we can print then out toofor i in elements:    print "Element was:%s" % i

修改：之前代码缩进有问题

3.

append() 方法向列表的尾部添加一个新的元素。只接受一个参数。 

extend()方法只接受一个列表作为参数，并将该参数的每个元素都添加到原有的列表中。