A preliminary study of Python

Learning Content:

1. Integrated Development Environment:

The classic text editor under VIM and Emacs#linux

Eclipse #Java IDE, Multiple languages supported

Visual Studio #微软开发的IDE, Multiple languages supported

notepad++,sublime, etc.

Pycharm is primarily used in the IDE for Python development

2. Formatted output mode

Placeholder%s: string,%d: integer,%f: floating-point number

Example:

Name = input ("name:"= input ("age:"= input ( " Salary: "  "-------------mes of%s------------Name =%sage =%ssalary =%s from retired time =% s--------------end----------------" % (name,name,age,salary,65-age )Print (msg)

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Function: make the output more flexible

3. Data operation

Integer: Integral type

Plural

Floating-point number: numbers with decimals

Boolean value: only two states: true (true) and False (false)

String

4. Circulation

For Loop:

Example:

 for  in range (0,100,4):    #0: start bit, 100: cut-off, 4: step    if i% 2 = = 0:          Print("loop:", I) for in range (1,101,2  ):    print("loop:", I)

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While loop

Example:

user ="a"passwd="b"C=0 whileC < 3: Username= Input (">>:") Password= Input (">>:")    ifuser = = Username andpasswd = =password:Print("wlecome%s to ..."%User) break    Else:        Print("user name or password is wrong, re-enter!") C+ = 1ifc = = 3: D= Input ("still want to play? y/n:")        ifD = ="y": C=0Else:    Print("Goodbye")

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You can add an else statement in a loop expression that represents a program that executes when the loop ends Normally.

5. Continue break

Continue means skipping this loop, which means ending the current loop

6. Flag Bit

Use a flag when you need to have a condition, or need a decision

7, Nested Loops

Used to implement multiple loop outputs, multi-layer selection menu.

8. List

An expression that uses the bracket flag to contain multiple contents, such as strings, integers, lists, tuples, dictionaries, and so On.

Cases:

A = ["name", 1,["Age","name"  ]]Print(a)

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List of queries

Check (slice)

A = [' I ', ' am ', ' siffre ', ' Thanks ']

Print (a)

Print (a[1:3]) #1, a third

Print (a[:3]) #开始, a third

Print (a[1:]) #1, and finally

Print (a[:]) #所有

Print (a[::2]) #步长

Print (a[1:-1]) #-1 represents the last, in turn -2,-3,-4

Print (a[1::-1]) #反向

Output:

[' I ', ' am ', ' siffre ', ' Thanks ']

[' am ', ' Siffre ']

[' I ', ' am ', ' siffre ']

[' am ', ' siffre ', ' Thanks ']

[' I ', ' am ', ' siffre ', ' Thanks ']

[' I ', ' Siffre ']

[' am ', ' Siffre ']

[' am ', ' I ']

Increment of List (add)

1) append, Add data to the last bit of the list

A = [' I ', ' am ', ' siffre ', ' Thanks ']

A.append (' you ') #在最后添加

Print (a)

Output:

[' I ', ' am ', ' siffre ', ' Thanks ', ' you ']

2) insert, Add data to the specified location in the list

A = [' I ', ' am ', ' siffre ', ' Thanks ']

A.insert (1, ' You ')

Print (a)

Output:

[' I ', ' You ', ' am ', ' siffre ', ' Thanks ']

Modification of the list

1) Modify by index

A = [' I ', ' am ', ' siffre ', ' Thanks ']

a[1] = ' Hello '

Print (a)

Output:

[' I ', ' Hello ', ' siffre ', ' Thanks ']

2) Modification by sectioning

A = [' I ', ' am ', ' siffre ', ' Thanks ']

a[1:2] = [' Hello ', ' World ']

Print (a)

Output:

[' I ', ' Hello ', ' world ', ' Siffre ', ' Thanks ']

Deletion of the list

1) remove deletes the specified content

A = [' I ', ' am ', ' siffre ', ' Thanks ']

A.remove (' I ') #指定切片也可以

Print (a)

Output:

[' am ', ' siffre ', ' Thanks ']

2) Pop Default Delete tail, You can also specify the index delete , after deletion will have a return value

A = [' I ', ' am ', ' siffre ', ' Thanks ']

A.pop ()

Print (a)

Output:

[' I ', ' am ', ' siffre ']

3) del Deletes the specified element by index, or it can delete the entire table

A = [' I ', ' am ', ' siffre ', ' Thanks ']

Del a[2]

Print (a)

Output:

[' I ', ' am ', ' Thanks ']

4) clear clears the contents of the list, preserves the list

A = ["name", 1,["age", "name"]]

A.clear ()

Print (a)

Output:

[]

9, List of functions

1) Count () Number of an element in the statistics list

A = [' i ', ' am ', ' siffre ', ' Thanks ', ' i ']

b = A.count (' I ')

Print (a)

Print (b)

Output:

[' i ', ' am ', ' siffre ', ' Thanks ', ' i ']

2

2) Extend () Add another list content to the current list , as Follows: b the list is Unchanged.

A = [' I ', ' am ', ' siffre ', ' Thanks ']

b = [1, 2, 3]

A.extend (b)

Print (a)

Output:

[' I ', ' am ', ' siffre ', ' Thanks ', 1, 2, 3]

3) index () queries the indexed value of an element

A = [' I ', ' am ', ' siffre ', ' Thanks ']

b = A.index (' am ')

Print (b)

Output:

1

4) reverse () Reverses the position of the elements in the list (the index changes)

A = [' I ', ' am ', ' siffre ', ' Thanks ']

A.reverse ()

Print (a)

Output:

[' Thanks ', ' siffre ', ' am ', ' I ']

5) sort () Sorts the elements in the list, the default ascending order, which can be reversed by sort (reverse=true), the numbers sorted by size, and the other characters by the ASC table corresponding values

A = [1, 5, 7, 33, 67, 2]

A.sort ()

Print (a)

Output:

[1, 2, 5, 7, 33, 67]

Determines whether the list contains the corresponding elements (in, count ())

A = [' I ', ' am ', ' siffre ', ' Thanks ']

If ' AM ' in a:

Print (' Yes ')

Else

Print (' No ')

Output:

Ok

A = [' I ', ' am ', ' siffre ', ' Thanks ']

b = A.count (' Hello ')

Print (b)

Output:

0 #表示没有

Identity judgment

A = [1, 5, 7, 33, 67, 2]

b = Type (a) is List

Print (b)

Output:

True

A preliminary study of Python