Third, the conversion between bool values, and the various functional attributes of str.

 

The conversion between bool values ​​and empty string is False and there is content in the string is True.

a = 11 
c = str(a)   # convert int to str 
print (type(c))

a = ' 123456 ' 
b = int(a)   # convert str to int 
print (type(b))

a = ''  #empty string is False 
print (bool(a))
b = '  '  #The content in the string is True 
print (bool(b))

Common functions of str (***important)

**
capitalize

capitalize() 

s = ' ZHANGyaJIe '

s1 = s.capitalize() #The first letter is capitalized, and the rest are all lowercase. 
print (s1)

*
center

s2 = s.center(27, '<') # center and fill 
print(s2)

***
upper
lower

s1 = s.upper() #all uppercase 
print(s1) 
s2 = s.lower() #all lowercase 
print(s2) 

implements a small function of verification code.

mode = 'AEad'.upper() 
name = input('Please enter the verification code').upper() 
if name == mode: 
    print('The output is successful')

*** 
startswith 
endswith
 s = 'laonanhai'
print(len(s))
s2 = s. startswith ('lao')#startswith is to judge what starts with (the judgment is not True, it is False)
s2 = s.startswith(' nan',3,6) # Can be sliced, slices are separated by commas, and the index starts from 0. 
s3 = s.startswith('ona',2,5) # Can be sliced, the slices are separated by commas, and the index starts from 0.

s1 = s.endswith('hai') 
s1 = s. endswith ('lao',0,3) #Can be sliced, the slices are separated by commas, and the index 0 starts (regardless of the head and the tail) 
print(s1)

*
swapcase

s = 'laonanhai' 
s1 = s.swapcase() # case flip

*
title

s = 'lao5nan4hai' 
s1 = s.title() #Separate non-letters, the first letter of each word is capitalized.

***
index

s = 'lao5nan4hai' 
s1 = s.index('4ha',7,10) #Find the index through the element, it can be sliced, and an error is not found.

s = 'ABCDEFG1AHIJAK' 
print(len(s)) 
s1 = s.find('DEFG', 2, 7,) Find the index by element, it can be sliced, if it is not found, return -1.

***
strip

name = input('please input').strip() #Remove leading and trailing spaces and newlines, tabs 
pwd = input('please input').strip() 
if name == 'zhang' and pwd == '123' : 
    print('Login successful'). 


*** 
split

s = 'zhang alex taibai' 
s1 = s.split()#Convert the string to list format. space-separated by default

s1 = s.split(',')#Convert string to list format. space-separated by default

***
join

li = ['zhang', 'alex', 'taibai'] 
s11 = ','.join(li) #Convert the list to str mode by join.

**
replace

s = 'Haha, Xiaofennen is just to pass a lot of things. Dog Xiaofennen broth is not ah, is it Xiaofennen?' 
s11 = s.replace('Xiaofennen','Big Hammer',2) #Only from Replace from left to right. Replacement is not possible from the right. 

***  
count

s = '2sdffhdyertdgdyhsfgdfhrgsdfg' 
at =s.count('f',0,6) #Find the number of occurrences in the element. 

*** 
format

msg = 'My name is {}, I am {} years old this year, and I have a hobby of {}'.format('MT',17,'playing basketball') 
msg ​​= 'My name is {0}, I am {1} this year, and my hobby is {2} , my name is still {0}'.format('MT',17,'basketball') 
msg ​​= 'My name is {name}, this year is {age}, and my hobby is {hobby}'.format(name ='MT', age =16,hobby='playing basketball') 

** 
isalpha 
isalnum 
isdigit

name ='zhangyajie1324' 
print(name.isalpha()) #Determine whether the string is composed of letters. 
print(name.isalnum()) #Determine whether the string is composed of letters or numbers 
print(name.isdigit()) #Determine whether the string is composed of numbers.