python 对文件的操作

观看的技术文来源：http://www.cnblogs.com/alex3714/articles/5717620.html
import sys
# data = open("yesterday",encoding='utf-8').read()#读取整个文件，在文件不大的情况
# print(data)
'''f = open("yesterday",encoding='utf-8') #文件句柄
data = f.readline()
print(data)

f = open ("yesterday2",'w',encoding='utf-8')#'w'实则是创建一个文件，会覆盖到原有文件的文件名，默认为'r'
#data = f.read()
#data2 = f.read()
#print(data)
f.write("WRTER")#io.UnsupportedOperation: not writable


f = open ("yesterday2",'a',encoding='utf-8')# 'a'=append 追加不覆盖原来的文件  io.UnsupportedOperation: not readable
f.write("\n 追加到新的一行\n")
data =  f.read()
print('---read',data)

f = open("yesterday", encoding='utf-8')
# 打印前5行  方法一
for i in range(5):
    print(f.readline())
for line in f.readline():
    print(line.strip())

#文件修改 打开一个文件，修改完后到一个新的文件
f = open("yesterday",'r',encoding = 'utf-8')
f_new = open("yesterday2",'w',encoding ='utf-8')
find_str =sys.argv[1]#用shell 简单替换
replace_str = sys.argv[2]
for line in f:#一行一行写入line
    if find_str in line :
        line =line.replace(find_str,replace_str)
    f_new.write(line)
f.close()
f_new.close()


#python开发规范 一行代码不多于80 个字符
#为了避免打开文件后忘记关闭，可以通过管理上下文,为了避免打开文件后忘记关闭，可以通过管理上下文
with open("yeaterday2",'r',encoding='utf-8') as f2 ,\
        open("yeaterday", 'r', encoding='utf-8') as f:
    for  line in f:
        print(line)
#面向对象：类->class
#面向对象：过程->def
#函数式编程：函数->def