使用python实现wc命令程序的功能的实例代码

#!/usr/bin/env python
#encoding: utf-8
# Author: liwei
# Function: wc program by python
 
from optparse import OptionParser
import sys,os
 
def opt():
 parser = OptionParser()
 parser.add_option('-c', '--char',
 dest='chars',
 action='store_true',
 default=False,
 help='only count chars')
 
 parser.add_option('-w', '--word',
 dest='words',
 action='store_true',
 default=False,
 help='only count words')
 
 parser.add_option('-l', '--line',
 dest='lines',
 action='store_true',
 default=False,
 help='only count lines')
 
 parser.add_option('-n', '--nototal',
 dest='nototal',
 action='store_true',
 default=False,
 help='don't print total information')
 
 options, args = parser.parse_args()
 return options, args
 
#print options
def get_count(data):
 chars = len(data)
 words = len(data.split())
 lines = data.count('
')
 return lines, words, chars
 
#if not options.chars and not options.words and not options
 
def print_wc(options, lines, words, chars, fn):
 if options.lines:
 print lines,
 if options.words:
 print words,
 if options.chars:
 print chars,
 print fn
 
def main():
 options, args = opt()
 
 if not (options.lines or options.words or options.chars):
 options.lines, options.words, options.chars = True, True, True
 
 
 if args:
 total_lines, total_words, total_chars = 0, 0, 0
 for fn in args:
 if os.path.isfile(fn):
 with open(fn) as fd:
 data = fd.read()
 lines, words, chars = get_count(data)
 print_wc(options, lines, words, chars, fn)
 total_lines += lines
 total_words += words
 total_chars += chars
 elif os.path.isdir(fn):
 print >> sys.stderr, '%s is a directory' %fn
 else:
 sys.stderr.write('%s: No such file or directory
' % fn)
 # 只有多个文件的时候会计算出total字段
 if len(args) > 1 and not options.nototal:
 print_wc(options, total_lines, total_words, total_chars, 'total')
 else:
 fn = ''
 data = sys.stdin.read()
 lines, words, chars = get_count(data)
 print_wc(options, lines, words, chars, fn)
 
if __name__ == '__main__':
 main()