python中seek函数的使用

1、seek函数

file.seek(off, whence=0)：从文件中移动off个操作标记（文件指针），正往结束方向移动，负往开始方向移动。如果设定了whence参数，就以whence设定的起始位为准，0代表从头开始，1代表当前位置，2代表文件最末尾位置。

2.例子

#!/usr/bin/env python3
from sys import argv
#arg[0] is seek.py, argv[1] is the input_file
input_file = argv[1]
 
def print_all(f):
	print(f.read())
	
def rewind(f):
	f.seek(0)
	
def print_a_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("Now let's rewind,kind of like a tape.")
 
rewind(current_file)
 
print("Now let's print three lines.")
 
current_line = 1
print_a_line(current_line,current_file)
 
current_line = current_line + 1
print_a_line(current_line,current_file)
 
current_line = current_line + 1
print_a_line(current_line,current_file)