Article directory
String Common Operations
Common operations on strings include:
- Get length:
len - Find what:
find,index,rfind,rindex - Judgment:
startswith,endswith,isalpha,isdigit,isalnum,isspace - Count occurrences:
count - Replacement content:
replace - Cut string:
split,rsplit,splitlines,partition,rpartition - Modify case:
capitalize,title,upper,lower - Space handling:
ljust,rjust,center,lstrip,rstrip,strip - String concatenation:
join
Note: In Python, strings are immutable! All string-related methods will not change the original string, but return a result. In this new return value, the result after execution is retained!
len
lenfunction to get the length of a string.
mystr = '今天天气好晴朗，处处好风光呀好风光'
print(len(mystr)) # 17 获取字符串的长度
look up
Find related methods, which are used in roughly the same way, but with slight differences.
1. find
Find whether the specified content exists in the string, if it exists, return the starting position index value of the first occurrence of the content in the string, if not, return -1.
Grammar format:
S.find(sub[, start[, end]]) -> int
Example:
mystr = '今天天气好晴朗，处处好风光呀好风光'
print(mystr.find('好风光')) # 10 '好风光'第一次出现时，'好'所在的位置
print(mystr.find('你好')) # -1 '你好'不存在，返回 -1
print(mystr.find('风', 12)) # 15 从下标12开始查找'风',找到风所在的位置试15
print(mystr.find('风光',1,10)) # -1 从下标1开始到12查找"风光",未找到，返回 -1
2. rfind
Similar to find()the function, but searches from the right.
mystr = '今天天气好晴朗，处处好风光呀好风光'
print(mystr.rfind('好')) # 14
3. index
Same as find()the method, except that when the find method is not found, -1 is returned, and when str is not found, an exception will be reported.
Grammar format:
S.index(sub[, start[, end]]) -> int
4. rindex
Similar index(), but starts from the right.
judgment
Python provides a very rich method that can be used to judge a string.
1. startswith
Determine whether the string starts with the specified content.
Grammar format:
S.startswith(prefix[, start[, end]]) -> bool
Example:
mystr = '今天天气好晴朗，处处好风光呀好风光'
print(mystr.startswith('今')) # True
print(mystr.startswith('今日')) # False
2. endswith
Determine whether the string ends with the specified content.
mystr = '今天天气好晴朗，处处好风光呀好风光"
print(mystr.endswith("风光")) # True
print(mystr.endswith("好风光")) # False
#### 3. isalpha
判断字符串是否全是字母字符。
```python
mystr = 'Hello'
print(mystr.isalpha()) # True
mystr = 'Hello123'
print(mystr.isalpha()) # False
4. also
Determines whether a string is full of numeric characters.
mystr = '12345'
print(mystr.isdigit()) # True
mystr = '123abc'
print(mystr.isdigit()) # False
5. the ice room
Determines whether a string is all alpha or numeric characters.
mystr = 'Hello123'
print(mystr.isalnum()) # True
mystr = 'Hello!123'
print(mystr.isalnum()) # False
6. isspace
Determines whether a string is full of space characters.
mystr = ' '
print(mystr.isspace()) # True
mystr = ' Hello '
print(mystr.isspace()) # False
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