python learning diary - basic data types

1. Operators

Assignment operator:

= - = = + etc.

Mathematical operators:

+ - * / ** % //

Member operator:

Determine whether something is included in something inside

in     not in

E.g:

# String 
name = "Powerpuff a" 
# character: 
N1 = "off" 
# sequences / substring: 
n2 = "Flying" 
IF N1 in name: 
    Print ( "Success") 
the else: 
    Print ( "Fail") 
# output Success 
IF N1 not in name: 
    Print ( "Success") 
the else: 
    Print ( "fail") 
# output to fail

Data types: numeric, string, Boolean (True / False)

Comparison operators:

Boolean value:

　　True true

　　False false

Equal to: ==

Greater than:>

Less than: <

Greater than or equal:> =

Less than or equal: <=

Does not mean:! = Or <>

Logical Operators:

Invert: not for example, not True and False

And: and

或：or

Sequence: a front to a rear operator

user=”ftxy"
pwd="123"
v= user=='ftxy' and pwd='123' or 1==1 and pwd='test'
print(v)
#输出True　　

 

Explain: and if it is connected to the front False, the latter expression is determined will not directly return False; or if it is connected to the front True, it is determined not everything after directly return True; So if you want to customize the order must be bracketed

2. The basic data types

Specific methods and properties of control + Right View

Digital (int):

a = 123

After a binary digit print (num.bit_length ()) # output digital conversion

int (str) string to digital

type (object) to view the object type

= A 'A' 
B = int (A, Base = 16) # 10 output; meaning hexadecimal string, which was converted to decimal shaping 
print (b.bit_length) # output shaping share memory the median space

String (str):

str (object) into a string of strong

Commonly used methods: join, split, find, strip, upper, lower, replace (and other parts of the explanation follows)

= name "ftXy" 
# capitalized 
Print (name.capitalize ()) 
# all lowercase 
print (name.casefold ()) 
of the total length of the first parameter represents # string to be generated, when the second is filled the characters (with spaces if there is no default) 
Print (name.center (20, "*")) # put the middle 
name.ljust (20, "*") # put the left 
name.rjust (20, "*") # put the right 
number # statistical character appears in the character string (support sequences, the starting position may be defined) 
Print (name.count ( "F")) 

name.encode encoding 
name.decode decoding 

determining whether to start or end xxx 
Print (name.endswith ( "")) 
Print (name.startwith ( "")) 
# x from the position of the string to find and return, the search may be defined starting position; not found returns -1 
Print (name.find ( "X")) 

# string variable Alternatively, as described in the case of output AM ftxy the I,. 19 
Test = "the I AM {name}, Age {}" 
Print (test.format (name = "ftxy",=. 19 Age)) 
Print (test.format_map ({name: "ftxy", Age:}. 19)) # incoming Dictionary

# Placeholder with 
Test = "the I AM {0}, {}. 1" 
Print (test.format ( "ftxy",. 19)) 
# determines whether only a string of digits and letters 
Print (name.isalnum ()) 
# Analyzing only if the string of letters, it is determined whether the number (commonly isdecimal), determines whether digital (② can be determined), it is determined whether the number (two can be determined) 
Print (name.isalpha (), name.isdecimal (), name. isdigit (), name.isnumeric ()) 
# create a table, the partition number in parentheses i.e., the string of parameters, insufficient \ t corresponding to the space filled 
Print (test.expandtabs (. 5)) 
# determines whether output as; If there \ False t this translation character returns 
name.isprintable () 
name.istitle () # determine whether the title, the first letter of each word are capitalized 
name.title () # becomes the title 
name.isupper () # judge capitalization 
name.islower () 
name.upper () # capitalized 
name.lower () 
"test" .join (name) # the name of this test separator characters spaced 
# pass argument string removed the same sequence; Removes the specified string 
name.strip ( 'XY') 
name.rstrip () # removed from the right 
name.lstrip () # removed from the left
Alternatively Batch # demo, to replace the name f is J 
MT str.maketrans = ( "f", "J") 
name.translate (MT) 

name.replace ( "f", "J",. 1) # The name is replaced by f j, the replacement of only a 
name.partition () # pass parameters in accordance with the partition, the number can not be specified, but the separator can get 
name.split () # partitioned into a list in accordance with parameters passed; default according separated by spaces can specify the number of the partition 
may not define parameters when # methods, method call parameters = (the count in the method, the parameter must Sub, start and end parameters can not) 
DEF count (Self, sub, start = None, end = None)

Basic operation (other data types can also be used):

Get string and the lower the index by a subscript character: name [0]

Get sequence: acquiring the first to the second sub-sequence name [0,2] to the second last acquired sequence name [1, -1]

Get string length: len (str)

for loop: for variable names in the string 

Note: Once you create will exist for a long string in memory, can not be modified; any revision or spliced, regenerates the string; no one used will be recycled

End of the whole cycle: break

The end of this cycle: continue

Help create digital: range (start, end, step)

# Print user input and index 
name = input ( "Please enter your name:") 
length = len (name) 
for i in the Range (length): 
    Print (i, name [i])

List (list):

Tuple (tuple):

Dictionary (dict):

Boolean value (bool):