def my_iterator(*args):
start, stop, step = 0, 1, 1
if not args:
raise TypeError('TypeError: my_iterator expected at least 1 arguments, got 0')
elif len(args) > 3:
raise TypeError("TypeError: my_iterator expected at most 3 arguments, got {}".format(len(args)))
if len(args) == 1:
stop = args[0]
if len(args) == 2:
start, stop = args
if len(args) == 3:
start, stop, step = args
while (stop - start) * step > 0:
yield start
start += step
for i in my_iterator(10, 20):
print(i)
print()
for i in my_iterator(10):
print(i)
print()
for i in my_iterator(10, 0, -2):
print(i)
?运行结果：
D:\Python-interpreter\python.exe D:/Python-code/main.py
10
11
12
13
14
15
16
17
18
19
0
1
2
3
4
5
6
7
8
9
10
8
6
4
2
Process finished with exit code 0
正则表达式：
pattern：正则表达式（匹配的对象）
string：待匹配的字符串
flags：模式（匹配的条件）
match：匹配
import re
str_test = "abcd"
pattern = "abc"
match_obj = re.match(pattern, str_test )
print(match_obj)结果：
D:\Python-interpreter\python.exe D:/Python-code/main.py
<re.Match object; span=(0, 3), match='abc'>
Process finished with exit code 0fullmatch：完全匹配，只有当?pattern—匹配的对象和 string—要匹配的字符串完全一样时返回Match object，否则为空
import re
str_test = "abcd123"
pattern = "abc"
test = "abc"
fullmatch_obj1 = re.fullmatch(pattern, str_test)
fullmatch_obj2 = re.fullmatch(pattern, test)
print(fullmatch_obj1)
print(fullmatch_obj2)
结果：
D:\Python-interpreter\python.exe D:/Python-code/main.py
None
<re.Match object; span=(0, 3), match='abc'>
Process finished with exit code 0
search：通过扫描字符串查找一个和正则表达式匹配的内容，返回Match objec，匹配不到为空
import re
str_test = "abcd123"
pattern = "abc"
search_obj = re.search(pattern, str_test)
print(search_obj)
# fullmatch_obj = re结果：
D:\Python-interpreter\python.exe D:/Python-code/main.py
<re.Match object; span=(0, 3), match='abc'>
Process finished with exit code 0
findall：找到所有，返回一个列表（匹配到的所有结果）
import re
str_test = "abcd123adef"
pattern = "a"
findall_obj = re.findall(pattern, str_test)
print(findall_obj)结果：
D:\Python-interpreter\python.exe D:/Python-code/main.py
['a', 'a']
Process finished with exit code 0
finditer：返回一个迭代器，且迭代器的每一个元素都是Match object
import re
str_test = "abcd123adef"
pattern = "a"
finditer_obj = re.finditer(pattern, str_test)
print(finditer_obj)
for i in finditer_obj:
print(i)结果：
D:\Python-interpreter\python.exe D:/Python-code/main.py
<callable_iterator object at 0x0000027A78CE3F10>
<re.Match object; span=(0, 1), match='a'>
<re.Match object; span=(7, 8), match='a'>
Process finished with exit code 0
split：分割
"""
split(pattern, string, maxsplit=0, flags=0)
pattern：正则表达式，匹配的对象
string：待匹配的字符串
maxsplit：最大分割次数
flags：模式，匹配的条件
"""
import re
str_test = "汽车,火车,飞机,磁悬浮列车,火箭,轮船"
pattern = ","
split_obj = re.split(pattern, str_test, 4)
print(split_obj)结果：前面已经分割四次，后面【'火箭,轮船'】未被分割
D:\Python-interpreter\python.exe D:/Python-code/main.py
['汽车', '火车', '飞机', '磁悬浮列车', '火箭,轮船']
Process finished with exit code 0
sub：替换
"""
sub(pattern, repl, string, count=0, flags=0)
pattern：匹配的对象
relp：replace：替换，替换的内容
count：替换的最大次数
"""
import re
str_test = "汽车,火车,飞机,磁悬浮列车,火箭,轮船"
pattern = ","
sub_obj = re.sub(pattern, " - ", str_test, 4)
print(sub_obj)
结果：前面已经替换四次，后面【'火箭,轮船'】中的【,】未被替换
D:\Python-interpreter\python.exe D:/Python-code/main.py
汽车 - 火车 - 飞机 - 磁悬浮列车 - 火箭,轮船
Process finished with exit code 0
subn：sub+number，与sub类似
import re
str_test = "汽车,火车,飞机,磁悬浮列车,火箭,轮船"
pattern = ","
subn_obj = re.subn(pattern, " - ", str_test, 4)
print(subn_obj)结果：返回一个元组，后面是替换次数
D:\Python-interpreter\python.exe D:/Python-code/main.py
('汽车 - 火车 - 飞机 - 磁悬浮列车 - 火箭,轮船', 4)
Process finished with exit code 0
complie：编译
"""
compile(pattern, flags=0):
"Compile a regular expression pattern, returning a Pattern object."
return _compile(pattern, flags)
def findall(pattern, string, flags=0):
return _compile(pattern, flags).findall(string)
def split(pattern, string, maxsplit=0, flags=0):
return _compile(pattern, flags).split(string, maxsplit)
def match(pattern, string, flags=0):
return _compile(pattern, flags).match(string)
def fullmatch(pattern, string, flags=0):
return _compile(pattern, flags).fullmatch(string)
def search(pattern, string, flags=0):
return _compile(pattern, flags).search(string)
def sub(pattern, repl, string, count=0, flags=0):
return _compile(pattern, flags).sub(repl, string, count)
def subn(pattern, repl, string, count=0, flags=0):
return _compile(pattern, flags).subn(repl, string, count)
在调用这些方法时都调用了_compile(pattern， flags)
可只执行一次_compile()提高效率
举例如下：
"""
import re
str_test = "abcd"
pattern = "abc"
compile_obj = re.compile(pattern)
data = compile_obj.match(str_test)
print(data)
结果：
D:\Python-interpreter\python.exe D:/Python-code/main.py
<re.Match object; span=(0, 3), match='abc'>
Process finished with exit code 0