Python：正则表达式＋文件处理

一、正则表达式

1.用法：使用Python的re模块，首先用re.compile() 函数，将正则表达式的字符串形式编译为Pattern实例，然后通过Pattern实例处理文本并获得匹配结果（Match实例），再通过Match实例做其他操作。

2.re模块中的match方法：只匹配字符串开始处的字符。3.re模块中的search方法：会匹配整个字符串。'''

# 1

pattern = re.compile('[a-zA-Z]')

match = pattern.findall('ddhfsaqugfa3412hdh21hhdGAAASAA')

print(match)

# 2

print(re.match('\d0','30ddd'))

# 3

print(re.search('\d0','ddd30ddd40ffff50hhh'))

# 1

pattern = re.compile('[a-zA-Z]')

match = pattern.findall('ddhfsaqddDDa3412h21hdGAA')

print(match)

# 2

print(re.match('\d0','30ddd'))

# 3

print(re.search('\d0','ddd30ddd40ffff50hhh'))

二、文件处理

1.打开文件：用open函数，参数为文件路径和打开方式，打开文件返回为fileObject类型

2.读取文件：read函数来处理fileObject类型文件

3.open(path,'x') x = w 是写（原文覆盖），x = r 是读 x = a 写（原文后面追加）

4.换行写入：在要写入的字符串前加/n

5：读写特定编码的文章：open(path,'r',encoding='gbk/utf-8')

6:读写一行：readline() readlines() writelines()

7:工程中出现异常，和安全性考虑：用with

path ='C://Text2.txt'

path1 ='C://Text3.txt'

# 1

file =open(path,'a')

# 2 3

file.write('嘻嘻嘻嘻')

file =open(path,'r')

print(file.read())

file =open(path,'a')

# 4

print(file.write('\njjjjj'))

file =open(path1,'w')

str_list = ['hello\n','world\n','hello hhh\n']

# 6

new_file = file.writelines(str_list)

print('new_file:',new_file)

file =open(path1,'r')

print('file.read:',file.read())

file =open(path1,'r')

print('file.readlines:',file.readlines())

path2 ='C://Text4.txt'

# 7

with open(path2,'w')as f:

print('write length:',f.write('hello world'))

path ='C:/Text2.txt'

path1 ='C:/Text3.txt'

# 1

file =open(path,'a')

# 2 3

file.write('嘻嘻嘻嘻')

file =open(path,'r')

print(file.read())

file =open(path,'a')

# 4

print(file.write('\njjjjj'))

file =open(path1,'w')

str_list = ['hello\n','world\n','hello hhh\n']

# 6

new_file = file.writelines(str_list)

print('new_file:',new_file)

file =open(path1,'r')

print('file.read:',file.read())

file =open(path1,'r')

print('file.readlines:',file.readlines())

path2 ='C:/Text4.txt'

# 7

withopen(path2,'w')asf:

print('write length:',f.write('hello world'))

今天先放点最简单的内容，以后用户多的话可能就每天更新了。