好久没写过Python了，前一阵子忙这忙那的，都几乎把Python给丢掉了，话不多说，马上开始。
其实这个题目比较基础，用shell语言的话，一行就能搞定。还是做一下吧。
用shell语言+正则：
dzhwen@deng:~/python文件/Homework/Chapter9$ cat regular_express.txt | grep -v ‘^#‘
用python:
1 #!/usr/bin/env python 2 #-*-coding=utf-8-*- 3 4 def show(filename): 5 f = open(filename,‘r‘) 6 for eachLine in f: 7 if eachLine[0] != ‘#‘: 8 print eachLine, 9 10 if __name__ == ‘__main__‘: 11 show(‘/home/dzhwen/regular_express.txt‘)
shell：
dzhwen@deng:~/python文件/Homework/Chapter9$ head -n N F
python:
1 #!/usr/bin/env python 2 #-*-coding=utf-8-*- 3 4 def head(): 5 filename = raw_input(‘请输入文件名称:‘) 6 lines = raw_input(‘请输入行数:‘) 7 start = 0 8 f = open(filename,‘r‘) 9 while start < int(lines): 10 print f.next(), 11 start += 1 12 13 if __name__ == ‘__main__‘: 14 head()
shell：
dzhwen@deng:~/python文件/Homework/Chapter9$ wc -l regu* 22 regular_express.txt
python:
>>> f = open(‘/home/dzhwen/regular_express.txt‘) >>> list = f.readlines() >>> len(list) 22
这道题目还是挺有挑战性的。用到的是sys模块的命令行参数
1 #!/usr/bin/env python 2 #-*-coding=utf-8-*- 3 4 import sys 5 6 def calc(): 7 f = open(‘/home/dzhwen/123.txt‘,‘a+‘) 8 list = sys.argv 9 if list[1] == ‘print‘: 10 for eachLine in f: 11 print eachLine, 12 return -1 13 if list[2] == ‘+‘: 14 ca = list[1:] 15 for char in ca: 16 f.write(char+‘ ‘) 17 f.write(‘\n‘) 18 f.write(str(float(list[1]) + float(list[3]))+‘\n‘) 19 if list[2] == ‘-‘: 20 ca = list[1:] 21 for char in ca: 22 f.write(char+‘ ‘) 23 f.write(‘\n‘) 24 f.write(str(float(list[1]) - float(list[3]))+‘\n‘) 25 if list[2] == ‘*‘: 26 ca = list[1:] 27 for char in ca: 28 f.write(char+‘ ‘) 29 f.write(‘\n‘) 30 f.write(str(float(list[1]) * float(list[3]))+‘\n‘) 31 if list[2] == ‘/‘: 32 ca = list[1:] 33 for char in ca: 34 f.write(char+‘ ‘) 35 f.write(‘\n‘) 36 f.write(str(float(list[1]) / float(list[3]))+‘\n‘) 37 if list[2] == ‘%‘: 38 ca = list[1:] 39 for char in ca: 40 f.write(char+‘ ‘) 41 f.write(‘\n‘) 42 f.write(str(float(list[1]) % float(list[3]))+‘\n‘) 43 if list[2] == ‘^‘: 44 ca = list[1:] 45 for char in ca: 46 f.write(char+‘ ‘) 47 f.write(‘\n‘) 48 f.write(str(float(list[1]) ** float(list[3]))+‘\n‘) 49 50 if __name__ == ‘__main__‘: 51 calc()
同时打开两个通道看可不可以。
#!/usr/bin/env python #-*-coding=utf-8-*- def copy(file1,file2): f = open(file1,‘r‘) g = open(file2,‘a+‘) for eachLine in f: g.write(eachLine) if __name__ == ‘__main__‘: copy(‘/home/dzhwen/123.txt‘,‘/home/dzhwen/456.txt‘)
shell:
dzhwen@deng:~/python文件/Homework/Chapter9$ cat regular_express.txt | grep ‘#‘ |wc -l 5
python：没有现成函数，唯有用count
1 #!/usr/bin/env python 2 #-*-coding=utf-8-*- 3 4 def charcount(filename): 5 num = raw_input(‘请输入字节值:‘) 6 Count = 0 7 f = open(filename,‘r‘) 8 for eachLine in f: 9 Count += eachLine.count(chr(int(num))) 10 return Count 11 12 if __name__ == ‘__main__‘: 13 print charcount(‘/home/dzhwen/regular_express.txt‘)
Python核心编程——Chapter9,布布扣,bubuko.com
原文：http://www.cnblogs.com/sysu-blackbear/p/3594636.html