Python基础_IO

poem = """\
Programming is fun
when the work is done 

if you wanna make your work also fun:
    use Python!
"""

# 打开文件以编辑（'w'riting）
f = open('poem.txt', 'w')
f.write(poem)
f.close()

# 如果没有特别指定，
# 将假定启用默认的阅读（'r'ead）模式
f = open('poem.txt')
while True:
    line = f.readline()
    # 零长度指示 EOF
    if len(line) == 0:
        break
    # 每行line的末尾
    # 都已经有了换行符
    # 因为它是从一个文件中进行读取的
    print(line, end='')
# 关闭文件
f.close()

输出：

Programming is fun
when the work is done
if you wanna make your work also fun:

use Python!

打开模式：阅读模式（'r'）、写入模式（'w'）、追加模式（'a'）

还可以选择是通过文本模式（'t'）还是二进制模式（'b'）来读取、写入或追加文本。

===============================================================
Character Meaning
--------- ---------------------------------------------------------------
'r' open for reading (default)
'w' open for writing, truncating the file first
'x' create a new file and open it for writing
'a' open for writing, appending to the end of the file if it exists
'b' binary mode
't' text mode (default)
'+' open a disk file for updating (reading and writing)
'U' universal newline mode (deprecated)

===============================================================

Pickle

标准模块，通过它你可以将任何春Python对象存储到一个文件中，并在稍后将其取回。这叫做持久地存储对象。

import pickle

shoplistfile = 'shoplist.data'
shoplist = ['apple', 'mango', 'carrot']

f = open(shoplistfile, 'wb')
pickle.dump(shoplist, f)
f.close()

del shoplist

f = open(shoplistfile, 'rb')
storedlist = pickle.load(f)
print(storedlist)

输出：['apple', 'mango', 'carrot']

dump函数——封装（Pickling）

load函数——拆封（UNpickling）

Unicode

# encoding=utf-8
import io

f = io.open("abc.txt", "wt", encoding="utf-8")
f.write(u"Imagine non-English language here")
f.close()

text = io.open("abc.txt", encoding="utf-8").read()
print(text)

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