[Python]文件

# -*- coding: utf-8 -*-

f = open('dairy.txt', 'w')
# 如果一个文件不存在会报异常, 写入模式让你能够写入文件，并在文件不存在时创建它。
# 在写入模式下打开文件时，既有内容将被删除（截断），并从文件开头处开始写入；如果要在既有文件末
# 尾继续写入，可使用附加模式

f1 = open('dairy1.txt', 'x')
# 独占写入模式不允许文件已存在

# -*- coding: utf-8 -*-

with open('dairy.txt', 'w') as f:
    f.write("真是寂寞如雪啊~")


with open('dairy.txt', 'r') as f:
    ctx = f.readline()
    print(ctx)

# -*- coding: utf-8 -*-

import sys
text = sys.stdin.read()
words = text.split()
wordcount = len(words)
print('Wordcount:', wordcount)

# cat .\dairy.txt | python .\script.py

# -*- coding: utf-8 -*-

with open('./dairy.txt', 'w+') as f:
    f.seek(5)
    print(f.tell())
    f.write("test")
    print(f.tell())

with open('./dairy.txt', 'r+') as f:
    f.seek(5)
    s = f.read(4)
    print(s)

# seek移动指针, tell返回指针位置

import fileinput
for line in fileinput.input(filename):
    process(line)

with open(filename) as f: 
    char = f.read(1) 
    while char: 
        process(char) 
        char = f.read(1)

# %%
with open(filename) as f: 
    while True:
    char = f.read(1) 
    if not char: break 
    process(char)

# %%
with open(filename) as f: 
    while True: 
        line = f.readline() 
        if not line: break 
        process(line)

# %%
with open(filename) as f: 
    for char in f.read(): 
        process(char)

# %%
with open(filename) as f: 
    for line in f.readlines(): 
        process(line)

# %% 文件是可迭代的
with open(filename) as f: 
    for line in f: 
        process(line)

# %%
for line in open(filename): 
    process(line)

# %% sys.stdin也是可迭代的
import sys 
for line in sys.stdin: 
    process(line)
# 这可以实现不用fileInput实现文件流输入, 使用管道符重定向个文件输入

# %%

# -*- coding: utf-8 -*-
import sys

f = open('./content.txt', 'w')
print('First', file=f)
print('Second', file=f)
print('Thrid', file=f)
# print的默认输出是sys.stdin, 重定向到文件
f.close()

with open('./content.txt') as f:
    print(list(f))