python基础(2)字符串常用方法

python字符串常用方法

 

find(sub[, start[, end]])

在索引start和end之间查找字符串sub
​找到,则返回最左端的索引值,未找到,则返回-1
​start和end都可省略,省略start说明从字符串开头找
省略end说明查找到字符串结尾,全部省略则查找全部字符串

source_str = "There is a string accessing example"
print(source_str.find('r'))
>>> 3

 

count(sub, start, end)

返回字符串sub在start和end之间出现的次数

source_str = "There is a string accessing example"
print(source_str.count('e'))
>>> 5

 

replace(old, new, count)

old代表需要替换的字符,new代表将要替代的字符,count代表替换的次数(省略则表示全部替换)

source_str = "There is a string accessing example"
print(source_str.replace('i', 'I', 1))
>>> There Is a string accessing example # 把小写的i替换成了大写的I

 

split(sep, maxsplit)

以sep为分隔符切片,如果maxsplit有指定值,则仅分割maxsplit个字符串
分割后原来的str类型将转换成list类型

source_str = "There is a string accessing example"
print(source_str.split(' ', 3))
>>> ['There', 'is', 'a', 'string accessing example'] # 这里指定maxsplit=3,代表只分割前3个

 

startswith(prefix, start, end)

判断字符串是否是以prefix开头,start和end代表从按个下标开始,哪个下标结束

source_str = "There is a string accessing example"
print(source_str.startswith('There', 0, 9))
>>> True

 

endswith(suffix, start, end)

判断字符串是否以suffix结束,如果是返回True,否则返回False

source_str = "There is a string accessing example"
print(source_str.endswith('example'))
>>> True

 

lower

将所有大写字符转换成小写
 

upper

将所有小写字符转换成大写
 

join

将列表拼接成字符串

list1 = ['ab', 'cd', 'ef']
print(" ".join(list1))
>>> ab cd ef

 

切片反转

list2 = "hello"
print(list2[::-1])
>>> olleh