函数和文件ex20

# -*- coding: utf-8 -*-
# @Author: yt
# @Date:   2018-05-15 13:55:12
# @Last Modified by:   yt
# @Last Modified time: 2018-05-15 14:57:53

from sys import argv

script,input_file = argv

#读取文件的所有内容
def print_all(f):
    print f.read()

#设置文件指针到文件起始位置
def rewind(f):
    f.seek(0)

#读出指定行的文件内容
def print_line(line_count,f):
    print line_count,f.readline()

current_file = open(input_file)

print "First let's print the whole file:\n"
print_all(current_file)

print "rewind,seek(0)"
rewind(current_file)

print "Let's print three lines:"

current_line = 1
print_line(current_line, current_file)

current_line += 1
print_line(current_line,current_file)

current_line += 1
print_line(current_line,current_file)

图1

seek(number): 设置文件的指针到指定的number处