Python Learning Diary 3/10

Part 1 if Judgment statement

Grammar rules

if Judge Condition:    Execute statement else:    EXECUTE statement

eg

Age_of_shen = 22Guess_age= Int (Input (">>:") )#The pseudo code is as follows" "if guess_age = = Age_of_shen then print ("yes") else print ("no")" "#code that conforms to the Python syntax rules is as followsifGuess_age = =Age_of_shen:Print("Yes,you got it.")Else:    Print("no,you is wrong.")

Part 2 Indent

Indentation Error:

Not indented:

Indentationerror:expected an indented block

tab! = Four spaces:

Indentationerror:unident dose not match no outer indentation level

Indents are equivalent to curly braces in other programming languages

Indentation level must be consistent, official rules knock four spaces

Syntax error: Syntaxerror:invalid Syntax

Native tab is not recommended, because win and Linux tab is not the same, cross-platform is all messed up

Therefore, in order to once and for all, you can replace the TAB function with four spaces, in notepad++, settings, preferences, language, check replace with a space

You can also display symbols in view, tick "show Spaces and Tabs," and the effect is as follows

　　

Part 3 operator

Arithmetic operators

Subtraction +-*/

Divisible//

Residual%

Exponential arithmetic * *

Exponential operator has precedence over subtraction

Comparison operators

Greater than > greater than or equal to >=

Less than > less than or equal to <=

equals = = Not equal to! =

"Note" links in Python that support comparison operators

eg

A = 2= 3= 1if c<a<B:    print ("True" )

Output Result:

"Practice" The user enters three numbers and outputs the maximum value

num_1 = Int (input ("NUM1:")) Num_2= Int (Input ("Num2:")) Num_3= Int (Input ("Num3:")) Max_num=0ifNum_1 >Num_2:max_num=num_1ifMax_num <Num_3:max_num=Num_3Else: Max_num=num_2ifNum_2 <Num_3:max_num=Num_3Print("Max Unmber is:"+str (Max_num))

Operation Result:

Assignment operator =

Plus + + + minus etc-= multiply etc *= except/=//% * *

Conditional operators

And or not to repeat

Expression: A code or statement consisting of operands and operators that can be placed on the right of a variable to assign a value to a variable

Short Circuit principle

Condition 1 and Condition 2 if condition 1 is false, condition 2 is no longer evaluated, direct output false

Condition 1 or Condition 2 condition 1 is true, condition 2 is no longer evaluated, direct output true

Part4 while loop

Grammar rules

 while condition:    Execute statement     #breakcontinue with C language

Basically the same as the C language

"Exercise" outputs 1-100 of all even numbers

Count = 1;  while count<=100:    if count%2 = = 0        :print  ( Count)    + = 1

"Exercise 2" Guess age-Enhanced Edition

Age_of_shen = 22Tag=False while  notTag:guess_age= Int (Input (">>:"))    ifGuess_age = =Age_of_shen:tag=TruePrint("Yes,you got it.")    elifGuess_age >Age_of_shen:Print("should try smaller")    Else:        Print("try bigger")

　　"Note" In Python the inverse operator is not, do not write C language write silly habitual use!

Operation Result:

"Exercise" Output 99 multiplication table

# 99 multiplication Table  = 1 while J <= 9:    = 1 while     i<= J:        print (str (i) +"*"+str (j) +"="+str (i*j), end=" \ t " )        + = 1    print(    )+ = 1

Output Result:

"Exercise 2" outputs a rectangle made up of "#", with a long width specified by the user

#output rectangle consisting of "#", long and wide specified by userHeight= Int (Input ("Height:")) Width= Int (Input ("Width:")) Num_height=0num_width=0 whilenum_height<Height:num_width=0 whilenum_width<Width:Print("#", end="") Num_width+ = 1Print() Num_height+ = 1

Output Result:

In Summary

　　1. Familiar with the IF statement in Python and the syntax rules of the while statement

While condition :

　　　　　　EXECUTE statement

If condition :

　　　　　　EXECUTE statement

elif conditions :

　　　　　　EXECUTE statement

　　　　Else Condition :

　　　　　　EXECUTE statement

The red part differs from the C language, so be sure to remember

2. Understand the while....else .... How to use

While condition:

Code

Else

Code

Code after the while loop performs the else after the normal end, and does not execute if there is a break

3. Learn the difference between tab and space, and learn the effect of switching tab in notepad++

4. Familiar with the operators in Python

　　　　With and

OR OR

Non-not

These three are different from C language, please remember

Python Learning Diary 3/10