14-day training camp for Python development-Chapter 1: python training camp

14-day training camp for Python development-Chapter 1: python training camp
Chapter 1 python Variables

Functions of Variables

Stored data is called and operated by the program

Mark data

Declare Variables

Name = "Ydh" variable name = variable value

Variable definition specification:

Variable names can only be any combination of letters, numbers, or underscores

The first character of the variable name cannot be a number.

The following keywords cannot be declared as variable names [python syntax keywords, python built-in variables]

Variable naming conventions

1. Camper (uppercase for each letter)

AgeOfOldboy = 56

NumberOfStudents = 80

2. Underline (officially recommended)

Age_of_oldboy = 56

Number_of_students = 80

Define the Low Mode of Variables

Variable name: Chinese and Pinyin

Variable Name Too Long

Variable name is not satisfactory

For example:

Your age = 20 age_of_oldboy = 20

Ni_denianling = 20

The_ni_de_mingzi = 20 your_name = 20

Name1 = 1

Name2 = "Beijing"

Call variable

Print (age_of_oldboy)

Modify variable value

Age_of_oldboy = 30

Constant

For example, π = 3. 14 .....

There is no special syntax in python to represent changliang. The programmer agreed that the constant variable names should all be capitalized.

For example, AGE_OF_OLDBOY = 20

Read user input

Input ()

Name = input ("input name :")

Note

Purpose:

1. Comment out unnecessary code

2. Describe the meaning of the code segment

Code annotation principles:

1. Do not add comments to all

2. You only need to add comments to what you think is important or hard to understand.

3. Annotations can be in Chinese or English, but do not use Pinyin.

Python Data Type

Basic Type

Number

Integer int

Long Integer

Float

Negative

Character Set

Text str

Bytes

Boolean

True/Flase

Dataset

List

Tuple

Dictionary dict

Ordered dictionary

Unordered dictionary

Set

Ordered Set

Unordered set

Int (integer)

On a 32-bit machine, the integer has 32 digits and the value range is-2.3 ~ 231-1

In a 64-bit system, the number of digits of an integer is 64-bit and the value range is-2.63 ~ 263-1

Long (long integer)

The Length Integer of python does not specify the bit width. That is to say, python does not limit the size of long integer values, but in fact, due to the limited memory of the machine, the long integer values we use cannot be infinitely large.

Float

A simple understanding is decimal

String

In python, the characters enclosed in quotation marks are considered as strings (including single quotation marks, double quotation marks, and three quotation marks)

There is no difference between single double quotation marks. The combination of single double quotation marks must be considered only in the following cases.

Msg = "I'm 20 years old! "

Multiple quotes are used to enclose strings with multiple quotes.

Msg = ''' I love the rise of the Sun on Tiananmen Square in Beijing ''' print (msg)

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String concatenation

Strings can be added and multiplied. Strings can only be concatenated with strings.

Name + age

Name * 10 print the name value 10 times

Boolean Type

True/False

It is used for logical judgment, whether it is True or False if it is incorrect!

Why do computers describe such a condition?

This is because it can be implemented based on the conditions, such:

if a > b : print ("this is a bigger number than b")else: print("this is a smaller number than b")

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Format output

% S represents a string

% D indicates a number

% F indicates float.

Operator

Arithmetic Operation

"+-*/, Take the remainder: %, power: ** x's y power, and take an integer //"

Comparison

"Equal to: =, not equal :! =, Not equal to: <>,>, <,> =, <="

Logical operation

"And, or, not"

Value assignment

"Equal to =, plus Equals + =, Minus equals-=, multiplication equals * =, Division equals/=, modulo equals % =, power equals ** =, and integer equals/ /="

Member operation

Identity Calculation

Bitwise operation

 

Process Control

Single Branch

If condition: the code to be executed after the condition is met

Dual Branch

If condition: the code to be executed after the condition is met. else: if the condition is not met, use the code here.

Multi-branch

If condition: the code elif to be executed after the condition is met: if the preceding condition is not met, the Code elif: if the preceding condition is not met, the Code elif: if the preceding conditions are not met, use this method.

While Loop

Syntax:

While condition: the condition is true and the code is executed...

 

Pass# Do nothing

 

Dead loop

count = 0while True:    print ("count:", count)    count += 1

 

Loop termination statement

Break is used to completely end a loop and jump out of the loop body to execute the following statement.

Continue jumps out of this loop and proceeds to the next loop

 

Exercise: Game of age Prediction

Exercise 1. Enter the name and gender to determine if a girl is a girl and print out my favorite girl. Otherwise, print them together to get the foundation!

Name = input ("input name:") sex = input ("input sex:") if sex = "female": print ("I like girls! ") Else: print (" get together! ") ''' Test result 1: input name: joininput sex! ----------- Test result 2: input name: Wei input sex: female I like girls! '''

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Exercise 2. Enter the name, gender, and age. If the girl is younger than 28 years old, print my favorite girl. Otherwise, print out the relationship between siblings!

Name = input ("input name:") sex = input ("input sex:") age = int (input ("input age :")) if sex = "female": if age <28: print ("I like girls") else: print ("it's good for siblings! ") ''' Test result 1: input name: Wei input sex: Female input age: 25 I like girls -------------- test result 2: input name: Wei input sex: Female input age: 29 siblings are also in love! Test result 3: input name: johninput sex: Male input age: 25: The output is empty.

View Code

Exercise 3. enter your name, gender, and age. If you are a girl and younger than 28 years old, print my favorite girl. Otherwise, print out my siblings! If you are a boy, print them together to get the foundation!

Name = input ("input name:") sex = input ("input sex:") age = int (input ("input age :")) if sex = "female": if age <28: print ("I like girls") else: print ("it's good for siblings! ") Elif sex =" male ": print (" get together! ") Else: print (" Incorrect sex input! ")

Exercise questions in this section

1. Process Control;

A small program that matches the score. The score has five ABCDE levels. The relationship with the score is as follows:
A 90-100
B 80-89
C 60-79
D 40-59
E 0-39

While True: score = float (input ("input your score:") if score> 100 or score <0: print ("No such score") elif score> = 90: print ("A") elif score> = 80 and score <= 89: print ("B") elif score> = 60 and score <= 79: print ("C ") elif score> = 40 and score <= 59: print ("D") elif score> = 0 and score <= 39: print ("E ")

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2. Exercise by guessing age

Exercise 1
Optimized the age-based game, allowing users to guess up to three times, right in the middle, and jump out of the loop directly

Name = 25 count = 1 while True: user_input = int (input ("Guess age, enter age:") if count> 3: break elif user_input = name: print ("Congratulations! ") Break count + = 1

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Exercise 2
Optimized the age-based game, allowing users to guess three times at most. After three times, they asked if they would continue to play,
If the user selects y, it is allowed three more times and cyclically. If the user inputs n, it exits the program.

Name = 25 count = 1 while True: if count> 3: while True: judge = input ("whether to continue playing the game, y/n :") if judge = "y": count = 0 break elif judge = "n": print ("Thank you! ") Exit () else: print (" incorrect input! ") Else: user_input = int (input (" Guess age, enter age: ") if user_input = name: print (" Congratulations! ") Break elif user_input <25: print (" think bigger !! ") Elif user_input> 25: print (" think smaller !! ") Count + = 1

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3. while loop exercises

Exercise 1. 1-100 cycles

count = 1while count <= 100:    print("loop:",count)    count += 1

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Exercise 2. an even number in the loop 1-100:

Count = 1 while count <= 100: if count % 2 = 0: # the even number can be divisible by 2. The opposite is the base print ("loop:", count) count + = 1.

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Exercise 3. Print the value from 1 to 100 cyclically, and do not print the value for 50th times. Print the square of the corresponding value for 60 to 80 times.

Count = 1 while count <= 100: if count = 50: pass if count> = 60 and count <= 80: print ("the square of loop count is :", count * count) else: print ("loop:", count) count + = 1

View Code

Exercise 4. loop termination statement

count = 1while count <= 100:    print("loop:",count)    if count == 5:        break    count += 1

View Codewhile else

While condition match: The condition matches successfully. Run the code else here: the condition does not match. Run the code here.

Example:

Count = 1 while count <= 5: # When count <= 5, the condition matches and runs print ("loop:", count) count + = 1 else: print ("loop terminated! ") # If count = 6 does not match the while condition, run the code here.

Output:

Loop: 1
Loop: 2
Loop: 3
Loop: 4
Loop: 5
The loop is terminated!

Assignments in this Chapter:

Basic requirements:
Ask the user to enter the user name and password
Welcome information displayed after successful authentication
Enter an error three times and exit the program.
Upgrade requirements:
You can log on to multiple accounts (Note: store multiple accounts in the list)
After three Authentication failures, the user exits the program,
When you attempt to log on again, the program is still locked (Prompt: You need to save the user's locked status to the file)