Syntax based user interaction python 1, the basic data types, output formatting, operator

Interact with the user:

Input:

python2:
            input一定要声明你输入的类型
            >>> input(">>:")
            >>:sean
            Traceback (most recent call last):
              File "<stdin>", line 1, in <module>
              File "<string>", line 1, in <module>
            NameError: name 'sean' is not defined
            >>> input(">>:")
            >>:"sean"
            'sean'
            >>> input(">>:")
            >>:1
            1
            >>> input(">>:")
            >>:[1,2]
            [1, 2]
            >>>

            -------------------------------
            >>> raw_input(">>:")
            >>:sean
            'sean'
            >>> raw_input(">>:")
            >>:12
            '12'

python3: 
            name = the INPUT ( " Please enter your name: " )   # receiving input from users, regardless of what type of user input, the final return must be a string 
            Print (name)
             Print (of the type (name)) 

the Result:　　

　　　　　　　　 SEAN
　　　　　　　　 <class 'str'>

Summary: raw_input and the same input python3 role in python2

 

Basic data types:

Data: description, measure the state of the data

Type: different things require different types of storage

int

　　python2:

　　　　In this interval [-24xxxxxxxx, 24xxxxxxxx]: int

　　　　If not in this range: long

　　python3：int

float

# The f2 converted to an integer, float switch must then transferred shaping 
f2 = ' 1.9 '     
f2 = a float (f2) 
f2 = int (f2)

complex (plural)

>>> a = 1-2j
>>> a
(1-2j)
>>> type(a)
<class 'complex'>
>>> a.real      #实部    
1.0
>>> a.imag     #虚部
-2.0  

str

　　python2: 8 bit bit sequence is the nature str

　　python3: unicode sequence is the essence str

= A ' the Hello ' 
B = ' World ' 
Print (A + B) 

Result: 
the HelloWorld 
# string concatenation, is to open up a new memory space , the value after splicing deposit into

list

= Y [ ' elephant ' , ' beautiful ' , [ ' Read ' , ' Study ' ]] 

Print (Y [0])      # print a list of the first element 

Print (Y [2] [0])       # printing of the third a list of elements, the first element read

dict：

Dictionary type #
# define methods: by braces store data by key: value for this mapping relationship defined key,
# key-value pairs each separated by a comma

D2 = { ' name ' : ' Tank ' , ' Age ' : 73 is, " Hobby " : [
     " basketball " ,
     " sister " 
]} 
Print (D2 [ ' name ' ])     # print name corresponding to the value of Tank 
Print ( D2 [ ' hobby ' ] [0])     # print hobby corresponding to a first list element basketball

bool

Boolean #
# is mainly used to determine right and wrong things
# generally does not define a separate boolean

"" " 
When the value equal to, not necessarily equal id 
id case of equality, the value is equal to the constant 
" "" 

Tag = True   # Tag = BOOL (True) 
Tag1 = False   # Tag = BOOL (False) 

Print (. 1 <2 ) 

a =. 1 
B =. 1
 Print (a == B)   # equals the comparison value 
Print (a iS B)   # iS comparison is id (address)

 

Formatted output:

Longhand

print("my name is",name,'my age is',age)

1,% s,% d placeholder:

% s: you can receive any type of variable
% d: receiving a digital only type
according to the delivery order, traditional values

Print ( " My name IS% S " % name)    　　
 Print ( " My name IS% S,% S IS My Age " % (name, Age))　　# If two or more parameters, enclosed in braces
 I = 1,232,314,241,412　　
Print ( "% .2f" I%)　　　　# 2 decimal places
 Print ( "% 0.2f"% I)　　　  # 2 decimal places

 

2、.format

print("my name is {} ,my age is {}".format(age,name))
print("my name is {name} ,my age is {age}".format(age=age,name=name))

 

. 3, F-String　　# python3.6 the characteristic

print(f"my name is {name} ,my age is {age}")

 

Operator:

Arithmetic operators:

# Arithmetic operators 
A =. 9 
B = 2 Print (A // B)   # rounding. Print (A% B)   # modulo Print (A ** B)   # Power ^ 2 9 # Comparison operators Print (A == B)   # left and right sides of the determined value of the operator are equal Print (A! = B)   # determination value left sides of the operator are not equal Print (a> B)
 Print (a> = B)
 Print (a < B)
 Print (a <= B) # assignment operator 
# incremental assignment 
a. 1 = 
a + = 1   #











. 1 = A + A 
Print (A) 

A - =. 1
 Print (A) 

A * = 2
 Print (A) 

A / = 2
 Print (A) 

# chain assignment 
X. 1 = 
Y =. 1 
Z =. 1 
X = Y = Z =. 1
 Print (X, Y, Z) 

# crossover assignment 
A, b = b, A    # A and b swap value 
Print (F " A: {A}, b: {b} " ) 

# decompression assignment 
l1 = [ 1,2,3,4,5,6 ] 
A = L1 [0] 
B = L1 [. 1 ] 
C = L1 [2] 
D = L1 [. 3 ]
 Print (A, B, C, D) 

A, B, C, D, * _ = L1   # * _ may receive an overflow element 
Print (A, B, C, D)     # . 1, 2,3,4   
 
* _, A, B, C, D = L1  
 Print (A, B, C, D)     # 3,4,5,6

logic operation:

And non-#
# and or not

. 1 = A 
B = 2 
C =. 3 Print (A <B and B> C)   # and: if there is a formula does not meet the conditions, whole expression are False Print (A <B or B <C)    # or : as long as there is a qualified expression, whole expression are True Print (Not a <B)   # negated Print (a <B and B <C or a> C)   # True # first determines (a <b) and (b <c or a> c ) and Print (A> B or B <C and A> C)   # False