1.字符串运算
- demo01
a='hello'
b="hello"
c='''hello'''
d='''
hello
'''
print(id(a))
print(id(b))
print(id(c))
print(id(d))
print(a == b)
print(a is b)
print(a == c)
print(a is c)
print(a == d)
print(a is d)
2393970514032
2393970514032
2393970514032
2393970514288
True
True
True
True
False
False
== 比较的是内容
is 比较的是地址
- demo02
#a, b均输入hello
a=input()
b=input()
print(a == b)
print(a is b)
print(id(a))
print(id(b))
hello
hello
True
False
1919556655472
1919556655536
input 函数会分配内存空间, 因此地址会改变
- demo03
a='hello'
b='me'
print(a+b)
print(a,b)
print(a*2)
hellome
hello me
hellohello
a='hello'
print('he' in a)
print('he' not in a)
True
False
name='lucy'
print('%s说%s'%(name, 'hello'))
lucy说hello
print("haha \'")
print(r"haha \'")
haha '
haha \'
name='hello67world'
print('1-->',name[0:5])
print('2-->',name[2:5])
print('3-->',name[2:])
print('4-->',name[:5])
print('-----------')
print('1-->',name[5:-1])
print('2-->',name[:-2])
print('3-->',name[-1:])
print('4-->',name[-5:-1])
print('-----------')
print('1-->',name[11:-1])
print('2-->',name[:])
print('3-->',name[-1:-5:-1])
print('4-->',name[-1:-5:-2])
print('5-->',name[5:0:-1])
print('6-->',name[5:0:1])
print('7-->',name[::-1])
print('8-->',name[::-2])
1--> hello
2--> llo
3--> llo67world
4--> hello
-----------
1--> 67worl
2--> hello67wor
3--> d
4--> worl
-----------
1-->
2--> hello67world
3--> dlro
4--> dr
5--> 6olle
6-->
7--> dlrow76olleh
8--> drw6le
2.字符串内嵌函数
- demo01
senence='hello world'
print('1-->',senence.capitalize())
print('2-->',senence.title())
print('3-->',senence.title().istitle())
print('4-->',senence.upper())
print('5-->',senence.lower())
1--> Hello world
2--> Hello World
3--> True
4--> HELLO WORLD
5--> hello world
- demo02 : 验证码案例.
random.randint():前闭后闭; randrange():前闭后开
import random
strs = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
code=""
for i in range(4):
code+=strs[random.randint(0, len(strs)-1)]
print("code:{}".format(code))
input_code = input("请输入验证码:")
if code.lower() == input_code.lower():
print("欢迎登陆")
else:
print("验证码输入错误")
code:Dcj6
请输入验证码:dcj6
欢迎登陆
- demo03: 查找与替换
senence='index lucy lucky left hands'
print('R' in senence)
print(senence.find('R'))
print(senence.find('l'))
print(senence.find('l', senence.find('l')+1, len(senence)-1))
False
-1
6
11
- demo04 :查找与替换
#find() rfind() lfind() index() rindex() lindex() replace()
url='http://image.baidu.com/search/2F20150704212949_PSfNZ.jpeg'
filename=url[(url.rfind('/')+1):]
print(filename)
2F20150704212949_PSfNZ.jpeg
- demo05 :中文转码
msg = "你好"
encode_msg = msg.encode("utf-8")
print(encode_msg)
decode_msg = encode_msg.decode("utf-8")
print(decode_msg)
b'\xe4\xbd\xa0\xe5\xa5\xbd'
你好
- demo06 :文件格式
path = "C:\test\picture.jpg"
filename = path[path.rfind('\\')+1:]
if filename.startswith('p') and filename.endswith('jpg'):
print('找到了')
else:
print('没找到')
找到了
- demo07 : msg.isalpha(), num.isdigit()
msg = "abd"
print(msg.isalpha())
sum = 0
for i in range(3):
num = input("请输入数字:")
if num.isdigit():
sum += int(num)
print (sum)
True
请输入数字:1
请输入数字:2
请输入数字:3
6
- demo08: '-'.join()
msg="hello"
new_msg = '-'.join(msg)
print(new_msg)
my_list = ['a', 'b', 'c']
result = ''.join(my_list)
print('result:', result)
print(type(result))
h-e-l-l-o
result: abc
<class 'str'>
- demo09: lstrip(), strip()
msg=' hello '
print(msg.lstrip()+'a')
print(msg.strip()+'a')
hello a
helloa
- demo10: split('-'), count('-')
msg = 'h-e-l-l-o'
print(msg.split('-', msg.count('-')))
print(msg.split('-', 2))
['h', 'e', 'l', 'l', 'o']
['h', 'e', 'l-l-o']
- demo11: 输入两个字符串s1, s2; s1中删除s2中的字符
s1 = input('s1:')
s2 = input('s2:')
for i in s2:
s1 = s1.replace(i, "")
print('s1:{}'.format(s1))
s1:hello world
s2:lo
s1:he wrd
- demo12: 输入一个str, 如果有小写字母或者叠词, 就提示
s1 = input('s1:')
for i in range(len(s1)):
if(s1[i] < 'A' or s1[i] > 'Z'):
print('有小写字母')
break
elif (i < len(s1) -1 and s1[i] == s1[i+1]):
print('有叠词')
D:\PythonStudying>python Demo03.py
s1:asd
有小写字母
D:\PythonStudying>python Demo03.py
s1:ASDD
有叠词
D:\PythonStudying>python Demo03.py
s1:ASDF
