编程读取文件指定行

1 #编写程序实现读取文件前几行
2 def print_line(file_name):
3     line = int(input('请输入要显示前几行：'))
4     f = open(file_name)
5     for each_line in range(0,line):
6         print(f.readline())
7 
8 file_name = input('请输入要打开的文件名：')
9 print_line(file_name)

 1 #编程实现读取指定行
 2 
 3 def print_content(file_name,lines):
 4 
 5     (former, latter) = lines.split(':',1)
 6     if former == '':
 7         former=1
 8     if latter == '':
 9         latter=-1
10     former = int(former)
11     latter = int(latter)
12 
13     if former==1 and latter == -1:
14         print('全文内容如下：')
15     elif latter == -1:
16         print('文件%s从第%d行到文件末尾内容如下：'% (file_name,former))
17     elif former == 1:
18         print('文件%s从开始到第%d行内容如下：'% (file_name, latter))
19     else:
20         print('文件%s从第%d行到第%d行的内容如下：' % (file_name, former, latter))
21 
22     f = open(file_name)
23     for each_line_num1 in range(former-1):
24         f.readline()
25     if (latter-former+1)< 0:
26         print(f.read())
27     else:
28         for each_line_num2 in range(latter-former+1):
29             print(f.readline())
30 
31     f.close()
32     
33 file_name = input('请输入要打开的文件:')
34 lines = input('请输入需要显示的行数【格式如13:21或 ：21 或21:】:')
35 print_content(file_name,lines)