1. Data type:
Digital (Integer, Long Integer, Floating Point, Complex)
String: Introducing bytes when introducing character encoding
List
Yuan Zu
Dictionary
Set

2. integer int
Function: Integer numbers such as grade/grade/ID number are correlated
Definition: age=10. Essentially age=int(10)

The decimal system is converted to... Binary system
 Print (bin (13)# Converts integer to binary
 Print (oct (13)# Converts integer to octal
 Print (hex (13)# Converts integer to hexadecimal

Common Operations + Built-in Methods

# Save a value

# Immutable
# x=10
# print(id(x))
# x=11
# print(id(x))

3. Floating-point float

Role: Wage/height/weight floating point correlation

 salary=3000.3 #essence salary=float(3000.3)

Type conversion

print(float(10))
print(float(1.1))
print(float('1.1'))

4. String type str

Role: Record the status of descriptive values, such as name/gender, etc.

msg='hello world' #msg=str('hello world')

Type Conversion: Any type can be converted to string type

res1=str(10)
res2=str(10.3)
res3=str([1,2,3])
res4=str({'x':1}) #res4="{'x':1}"

Common Operations + Built-in Approaches

1. Value by index (forward + reverse): only

msg='hello world'

print(type(msg[0]))
print(msg[-1])

msg[0]='H'

2. Slices (head without tail, step length)

msg='hello world'
print(msg[0]+msg[1]+msg[2])
print(msg[0:5])
print(msg[0:5:2]) 
print(msg[0:]) 
print(msg[:]) 

print(msg[-1:-5:-1]) #-1 -2 -3 -4
print(msg[::-1]) #-1 -2 -3 -4

3. Length len: The number of characters counted

4. Membership operations in and not in: Determine whether a subcharacter exists in a large string

# msg='hello world'
# print('ho' in msg)
# print('ho' not in msg)

5. Remove the blank strip: Remove some characters on the left and right sides of the string

msg='      hello      '

print(msg.strip(' '))
print(msg.strip())
print(msg)

name=input('name>>>: ').strip() #name='egon'
pwd=input('password>>>: ').strip()

if name == 'egon' and pwd == '123':
    print('login successfull')
else:
    print('username or password error')

msg='***h**ello**********'
print(msg.strip('*'))

msg='*-=+h/ello*(_+__'
print(msg.strip('*-=+/(_'))

6. Segmentation split: To cut regular strings into lists to facilitate the selection of values

info='egon:18:180:150'
res=info.split(':',1)
print(res)
print(res[1])


info='egon:18:180:150'
res=info.split(':')
print(res)


s1=res[0]+':'+res[1]+':'+res[2]+':'+res[3]
s1=''
for item in res:
    s1+=item
print(s1)


s1=':'.join(res)
print(s1)

':'.join([1,2,3,4,5])

7. cycle

for i in 'hello':
    print(i)

****** Operations to be mastered

1.strip , lstrip , rstrip 

msg='*****hello****'
print(msg.strip('*'))
print(msg.lstrip('*'))
print(msg.rstrip('*'))

2.lower , upper

msg='AaBbCc123123123'
print(msg.lower())
print(msg.upper())

#After execution
#aabbcc123123123
#AABBCC123123123

3. startswith , endswith

msg='alex is dsb'
print(msg.startswith('alex'))
print(msg.endswith('sb'))

#After execution
#True
#True

4. Three Plays of Form

msg='my name is %s my age is %s' %('egon',18)
print(msg)

#After execution
#my name is egon my age is 18

msg='my name is {name} my age is {age}'.format(age=18,name='egon')
print(msg)

#After execution
#my name is egon my age is 18

msg='my name is {} my age is {}'.format(18,'egon')
msg='my name is {0}{0} my age is {1}{1}{1}'.format(18,'egon')
print(msg)

#After execution
#my name is 1818 my age is egonegonegon

5.split , rsplit 

cmd='get|a.txt|33333'
print(cmd.split('|',1))
print(cmd.rsplit('|',1))

#After execution
#['get', 'a.txt|33333']
#['get|a.txt', '33333']

6. replace 

msg='kevin is sb kevin kevin'
print(msg.replace('kevin','sb',2))

#sb is sb sb kevin

7. isdigit (True when the string is a pure number)

res='11111'
print(res.isdigit())
int(res)

#True

age_of_bk=18
inp_age=input('your age: ').strip()
if inp_age.isdigit():
    inp_age=int(inp_age) #int('asdfasdfadfasdf')
    if inp_age > 18:
        print('too big')
    elif inp_age < 18:
        print('to small')
    else:
        print('you got it')
else:
    print('Pure numbers must be entered')

* * (understand)

1.find, rfind, index, rindex, count

find and index are similar in usage. find is more powerful than index. find is preferred.

print('xxxkevin is sb kevin'.find('kevin'))
print('xxxkevin is sb kevin'.index('kevin'))
print('xxxkevin is sb kevin'.rfind('kevin'))
print('xxxkevin is sb kevin'.rindex('kevin'))

#After execution
3
3
15
15

print('kevin is kevin is kevin is sb'.count('kevin'))

#After execution
# 3

2. center, ljust ,rjust , zfill

print('egon'.center(50,'*'))
print('egon'.ljust(50,'*'))
print('egon'.rjust(50,'*'))
print('egon'.zfill(50))

#After execution
***********************egon***********************
egon**********************************************
**********************************************egon
0000000000000000000000000000000000000000000000egon

 3. captalize , swapcase , title

print('my name is kevin'.capitalize())
print('AaBbCc'.swapcase())
print('my name is kevin'.title())

#After execution
My name is kevin
aAbBcC
My Name Is Kevin

4.is other

name='egon123'
print(name.isalnum()) #Strings consist of letters or numbers
print(name.isalpha()) #Strings consist of only letters

print(name.islower())
print(name.isupper())
name='    '
print(name.isspace())
msg='I Am Egon'
print(msg.istitle())


#After execution
True
False
True
False
True
True