Common methods of python string

Directory 1, find (sub [, start [, end]) 2, count (sub, start, end) 3, replace (old, new, count) 4, split (sep, maxsplit) 5, startswith (prefix, start, end) 6, endswith (suffix, start, end) 7, lower8, upper9, join10, slice inversion

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

In the index start And end Look up strings between sub
If found, the leftmost index value is returned; If not found, the index value is returned -1
​ start And end Can be omitted, omitted start Explain finding from the beginning of a string
Omission end Explain that the end of the string is found, and all strings are found if all are omitted

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

2. count (sub, start, end)

Return string sub In start And end Number of occurrences between

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

3. replace (old, new, count)

old Represents the character to be replaced, new Represents the character to be replaced, count Represents the number of replacements (omission means all replacements)

source_str = "There is a string accessing example"
print(source_str.replace('i', 'I', 1))
>>> There Is a string accessing example #  Put lowercase i Replaced with capitalized I
 

4. split (sep, maxsplit)

With sep Is a delimiter slice, if maxsplit If there is a specified value, only the partition maxsplit String
After segmentation, the original str type will be converted to list Type

source_str = "There is a string accessing example"
print(source_str.split(' ', 3))
>>> ['There', 'is', 'a', 'string accessing example'] #  Here you specify maxsplit=3 Represents only before division 3 A 
 

5. startswith (prefix, start, end)

Determines whether the string is based on the prefix At the beginning, start And end Represents which subscript begins and which subscript ends

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

6. endswith (suffix, start, end)

Determines whether the string is used with sub1 End, if it is returned True Otherwise, return False

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

7. lower

Convert all uppercase characters to lowercase

8. upper

Converts all lowercase characters to uppercase

9. join

Splice a list into a string

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

10. Slice inversion

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