“本地数据获取”的综合编程迷你项目

(1) 创建一个文件Blowing in the wind.txt，其内容是：    #问题非原创

How many roads must a man walk down

Before they call him a man

How many seas must a white dove sail

Before she sleeps in the sand

How many times must the cannon balls fly

Before they‘re forever banned

The answer my friend is blowing in the wind

The answer is blowing in the wind

(2) 在文件头部插入歌名“Blowin’ in the wind”

(3) 在歌名后插入歌手名“Bob Dylan”

(4) 在文件末尾加上字符串“ 1962 by Warner Bros. Inc.”

>>> f = open(r'Blowing in the wind.txt','w')
>>> f.write('How many roads must a man walk down\nBefore they call him a man\nHow many seas must a white dove sail\nBefore she sleeps in the sand\nHow many times must the cannon balls fly\nBefore they\'re forever banned\nThe answer my friend is blowing in the wind\nThe answer is blowing in the wind')
278
>>> f.close()
>>> f = open(r'Blowing in the wind.txt')
>>> line = f.readlines()  #将数据从源文件中一行一行地读出来，作为一个列表返回。
>>> line.insert(0, "Blowin' in the wind\n")
>>> line.insert(1, 'Bob Dylan\n')
>>> line.append('\n1962 by Warner Bros.Inc.')
>>> f.close()
>>> f = open(r'Blowing in the wind.txt','w')
>>> f.writelines(line)
>>> f.close()

补充：list

用len()函数可以获得list元素的个数;

用索引来访问list中每一个位置的元素，记得索引是从0开始的:list[0]

list中追加元素到末尾:list.append()

把元素插入到指定的位置，比如索引号为1的位置:list.insert(1,元素)

删除list末尾的元素，用pop()方法:list.pop()

删除指定位置的元素，用pop(i)方法，其中i是索引位置:list.pop(i)

把某个元素替换成别的元素，可以直接赋值给对应的索引位置:list[1]
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