Python字符串函数

Python字符串处理函数总结

      本文为Python字符串处理使用方法，直接 Ctrl + f 搜索关键字即可，方便自己使用。

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bit_length()   #计算二进制字符串

sum = 10
v=sum.bit_length()
print(v)
输出 4

upper() #小写转大写

aa = guoqingkuaile
upper(aa)
输出: GUOQINGKUAILE

lower() #大写转换成小写

test = "WELCOME"
v = test.lower()
print(v)
输出: welcome

capitalize()  #将字符串的第一位改成大写

test = "welcome"
v = test.capitalize()
print(v)
输出: Welcome

center(20,"*") # 20表示总长度，*代表空格用什么填充

test = Welcome
v = test.center(20,"*")
print(v)
输出: ******Welcome*******

endswith('x') #如果匹配字符串以x结尾，那么返回True，否则flase

test = "welcome"
v = test.endswith('x')
print(v)
输出: False

test = "welcomex"
v = test.endswith('x')
print(v)
输出: True

startswith #如果匹配字符串以x开头，那么返回True，否则flase

test = "welcome"
v = test.endswith('x')
print(v)
输出: False

test = "xwelcome"
v = test.endswith('x')
print(v)
输出: True

find() #如果找到此方法返回的索引，否则返回-1。
 

test = "welcome"
v = test.find('el',1,5)
print(v)
输出: 1

test = "welcome"
v = test.find('a',1,5)
print(v)
输出: -1

format() #格式化，将一个字符串中的占位符替换为指定的值

test = 'i am {name}, age {n}'
v = test.format(name='yunwei',n=21)
print(v)
输出: i am yunwei, age 21

#根据出现的顺序替换
test = 'i am {0}, age {1}'
v = test.format('yunwei',21)
print(v)
输出: i am yunwei, age 21

isalnum() #判断字符串中只包含数字和字母

test = "This year is 2019"
v = isalnum(test)
print(v)
输出: False

test = "goodbuy2018"
v = isalnum(test)
print(v)
输出: True

expandtabs(20) #20表示字符串长度为20，当匹配到\t时候，不足20用空白字符填充。

test = "username\tpassword"
v = test.expandtabs(20)
print(v)
输出: username          password

isalpha() #如果字符串所有都为字母则返回Ture

test = "welcome"
v = test.isalpha()
print(v)
输出: True

test = "welcome!!"
v = test.isalpha()
print(v)
输出: flase

isspace() #如果字符串所有都是空格，那么则返回True

test = "    "
v = test.isalpha()
print(v)
输出: True

istitle() #判断首字母是否是大写,是则返回True

test = "Welcome"
v = test.istitle()
print(v)
输出: True

islower() #判断字符串是否为小写

test = "welcome"
v = test.islower()
print(v)
输出: True

test = "Welcome"
v = test.islower()
print(v)
输出: Flase

lower() #将字符串变为小写字符

test = "WELCOME"
v = test.lower()
print(v)
输出: welcome

isupper() #判断字符串是否为大写

test = "WELCOME"
v = test.isupper()
print(v)
输出: True

test = "Welcome"
v = test.isupper()
print(v)
输出: Flase

upper() #将字符串变为大写字符

test = "Welcome"
v = test.upper()
print(v)
输出: WELCOME

title() #将字符串转换为标题，其首字母为大写

test = "welcome come to guangzhou"
v = test.istitle()
print(v)
输出: Welcome Come To Guangzhou

 

join() #每一个元素按照分隔符进行拼接

test = "国庆快乐"
v = "_".join(test)
print(v)
输出: 国_庆_快_乐

ljust(20,"*") #向右填充*字符，总长度为20

test = "lalalalala"
v = ljust(20,"*")
print(v)
输出: lalalalala**********

rjust(20,"*") #向做填充*字符，总长度为20

test = "lalalalala"
v = ljust(20,"*")
print(v)
输出: **********lalalalala

清除字符
rstrip() #默认清除右边空白字符
lstrip() #默认清除左边空白字符
strip()  #默认清除两边空白字符

maketrans() #对应字符替换

test = "abcdefg"
m = str.maketrans("acf","123")
c = test.translate(m)
print(c)
输出为 1b2de3

rpartition("co") #从目标字符串的末尾也就是右边开始搜索分割符,分割符会显示。

test = "comecomecome"
v = test.rpartition("co")
print(v)
输出: 'comecome', 'co', 'me'

split('co',1) #以co为分隔符分割正序，不包含分割的元素，1表示以第一个co为分割符

test = "comecomecome"
v = test.split("co", 1)
print(v)
输出: '', 'mecomecome'

replace("18","21",1) #字符串替换,1表示替换第一个18.

test = "i am 18 years"
v = test.replace("18","21",1)
print(v)
输出: i am 21 years

range(0,100,5) #创建连续的数字，0-99 ,5表示等差

test = range(0,100,5)
for n in test:
	print(n)
输出:
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
#pyton 3.x版本只有用for循环才会存入内存，