# -*- coding: UTF-8 -*-
f = open("/pythontab/code.txt") # 返回一个文件对象
line = f.readline() # 调用文件的 readline()方法
while line:
  # print line,   # 在 Python 2中，后面跟 ',' 将忽略换行符
  print(line, end='') # 在 Python 3中使用
  line = f.readline()
f.close()

代码如下:
# -*- coding: UTF-8 -*-
f = open("/pythontab/code.txt")
while 1:
  lines = f.readlines(10000)
  if not lines:
    break
  for line in lines:
    print(line)
f.close()

# -*- coding: UTF-8 -*-
for line in open("/pythontab/code.txt"):
  # print line, #python2 用法
  print(line)

import fileinput
for line in fileinput.input("/pythontab/code.txt"):
  print(line)