One: data types are converted to each other: Numbers and strings: int ----> str str(int) str ----> int int(str) can only be a string of numbers number and bool int ----> bool 0 Fasle non-zero True bool ----> True T ---> 1 F --->0 String and bool value str ---> bool non-empty True empty is False bool ----> str str(True) str(False) ''' i = bool(3) # print(i) # i1 = bool(0) # print(i1) # i = int(True) # print(i) # i = int(False) # print(i)
Two: the code runs faster
Three: Slicing and Indexing
s='alex wusir ritian'
Output the results separately:
You can also cut in the opposite direction and increase the step length
s1 = s[0:3:2] print(s1) s2 = s[-1:-6:-2] print(s2)
result:
Four: String usage
Common methods for strings
s = 'alex wuSir'
*capitalize() first letter is capitalized, other letters are lowercase
print(s.capitalize())
*swapcase() case inversion
print(s.swapcase())
Non-letter-separated parts, first letter uppercase, other lowercase
s = 'alex wuSir1taibai*ritian'
print(s.title())
s = 'alexawuSir'
***upper all caps
***lower all lowercase
print(s.upper())
print(s.lower())
code = 'aeDd'
your_code = input('Please enter the verification code:')
if your_code.upper() == code.upper():
print('input is correct')
else :print('Please re-enter')
* Centered by what, the padding is empty by default
print(s.center(20))
print(s.center(20,'*'))
s = 'al\tex wuSir'
print(s.expandtabs())
***find() finds the index through the element, you can find it as a whole, you can slice it, and return -1 if it is not found
index() finds the index through the element, which can be found as a whole, can be sliced, and an error will be reported if it is not found
print(s.find('a'),type(s.find('a')))
print(s.find('alex'),type(s.find('a')))
print(s.find('a'))
print(s.find('a',1,5))
print(s.find('L'))
print(s.index('L'))
s = 'alex wusir'
*** startswith endswith
print(s.startswith('a'))
print(s.startswith('al'))
print(s.startswith('w',5))
print(s.startswith('W',5))
print('adfads\n','fdsa')
print(s)
s = '\talex wusir\n'
s1 = 'alalelllllllxwusirbl'
*****strip removes spaces, newlines, tab keys, etc.
print(s.strip())
print(s.lstrip())
print(s.rstrip())
print(s1.strip('lab'))
name = input('Please enter the name:').strip()
if name == 'alex':
print('somebody')
else :print('Please re-enter')
s = 'alex;wusir;ritian'
s1 = 'alexalaria'
******split str --->list method
print(s.split(';'))
print(s.split(';'))
print(s1.split('a',1))
replace ******
s1 = 'Sister and brother come together old boy old boy old boy'
s2 = s1.replace('old', 'small', 1)
print(s2)
name='jinxin123'
print(name.isalnum()) #The string consists of letters or numbers
print(name.isalpha()) #The string consists only of letters
print(name.isdigit()) #The string consists only of numbers
Five: format usage:
format
The first
s = 'My name is {}, this year{}, height{}'.format('Jin Xin',21,175)
print(s)
the second
s = 'My name is {0}, this year is {1}, my height is {2}, my name is still {0}'.format('Jin Xin',21,175)
print(s)
the third
s = 'My name is {name}, this year {age}, height {high}'.format(name = 'Jin Xin',high=175,age=21)
print(s)
### public methods
count counts the number of times an element appears
s = 'alexaaaaa wusir'
print(s.count('a'))
s = 'alex'
print (len (s))