字符串常见操作

my_str = 'hello world neuedu and neueducpp'

• find()
  检查ｓｔｒ　中是否包含在　my_str中，如果在返回开始的索引值，否则返回－１

 index1 = my_str.find('neuedu')
 print(index1)

 index2 = my_str.find('neuedu', 0 , 10)
 print(index2)

• index()
  跟ｆｉｎｄ（）一样 只不过ｓｔｒ不在ｍｙｓｔｒ中要报一个异常

index3 = my_str.index('neuedu', 0 , 10)
 print(index3)

• count　返回　目标字符串出现的次数

 count = my_str.count('neuedu',0, 20)
 print(count)

• replace
  ￥599 ------> 599

name = 'hello world haha'
 new_name = name.replace('ha', 'Ha')
 print(new_name)
 name = 'hello world haha'
 new_name = name.replace('ha', 'Ha', 1)
 print(new_name)
 price = "￥599"
 price = price.replace('￥', '')
 print(price)

• split()
  以ｓｔｒ为分隔符分割ｎａｍｅ，如果ｍａｘｓｐｌｉｔ指定值，那么仅分割ｍａｘｓｐｌｉｔ个子串

 name = 'hello world ha ha'
 name_list = name.split(" ")
 print(name_list)
 name_list1 = name.split(" ", 2)
 print(name_list1)

• capitalize()把字符串的一个字符大写

 my_str2  = my_str.capitalize()
 print(my_str2)

• title() 把字符串的每个单词首字母大写

my_str3 = my_str.title()
print(my_str3)

• startswith 检测字符串是否以ｓｔｒ为开头

my_str4 = my_str.startswith('hello')
print(my_str4)
my_str5 = my_str.startswith('Hello')
print(my_str5)

• endwith() 检测字符串是否以ｓｔｒ为结尾

my_str6  = my_str.endswith('cpp')
print(my_str6)

• upper 把字符串的所有变为大写

my_str7 = my_str.upper()
print(my_str7)

• lower 字符串的所有变为小写

my_str8 = my_str7.lower()
print(my_str8)

• rjust 返回一个原字符串右对齐的并用空格填充　ｗｉｄｔｈ长度的新字符串

my_str_space = 'hello'
new_my_str_space = my_str_space.rjust(10)
print(new_my_str_space)

• ljust 返回一个原字符串左对齐对对齐的并用空格填充　ｗｉｄｔｈ长度的新字符串
  new_my_str_space1 = my_str_space.ljust(100)
  print(new_my_str_space1)
  print(len(new_my_str_space1))
• center()

new_my_str_space2 = my_str_space.center(50)
print(new_my_str_space2)
print(len(new_my_str_space2))

• lstrip 清除字符串左边的空白字符

print(new_my_str_space2)
print(len(new_my_str_space2)) # 50
new_str2 = new_my_str_space2.lstrip()
print(len(new_str2))
print(new_str2)

• rstrip()清除字符串右边的空白字符

new_str3 =new_str2.rstrip()
print(len(new_str3)) # 5
print(new_str3)

• strip() 删除两端的空白字符

str1 = '\n\tdadadad\t'
print(len(new_my_str_space2))
new_str4 = new_my_str_space2.strip()
print(len(new_str4))
print(len(str1))
str2 = str1.strip()
print(len(str2))

• find ---> rfind

index5 = my_str.rfind('neuedu')
print(index5)

• rindex ------> index
• partition 把mystr以str分割成3部分 str前，str str后

print(my_str)
t_mystr = my_str.partition('neuedu')
print(t_mystr) # 元组

• rpartition 从右边开始把mystr以str分割成3部分 str前，str str后
• splitlines 按照行分隔，返回一个包含各行作为元素的列表

line = 'hello\nworld'
print(line)
list_line = line.splitlines()
print(list_line)

• isalpha 判断字符串是否都是字母 True

alpha = my_str.isalpha()
print(alpha)
alpha2 = 'dddddddd'
alpha3 = alpha2.isalpha()
print(alpha3)

• isdigit
• isalnum 判断是否只有字母或者数字
  alpha2.isalnum()
• isspace
• join()

str4 = " "
list1 = ['my','name','is','songxiaobao']
 my_name = str4.join(list1)
 print(my_name)
  _  / ,
my_name = ",".join(list1)
print(my_name)

常用的find count replace split join strip