Python Learning Notes (iii) conditional judgments and loops

1. Conditional Judgment Statement

The keywords for conditional selection statements in Python are: If, elif, else three. Its basic form is as follows:

AGE_OF_CC = 27age = Int (Input ("Guessage:")) if Age = = age_of_cc:    print ("Yes,you got It!") Elif Age > AGE_OF_CC:    print ("Big guess!") else:    print ("Guess small!") ")

If statement execution is characterized by judging from the top down;

Where the elif and else statement blocks are optional. The branch statement executes only if and elif are judged true, and the Else branch is executed only if and all of the elif's judgments are false. Note in the conditional selection statement in Python, there is a colon behind the judgment.

2. Looping statements2.1 While Loop

Usage:

While condition:     xxxxxx

The while loop executes the statement that is subordinate to it until the condition is False (false)

2.1.1 Break Skip Loop

code example:

AGE_OF_CC = 27Count=0 whileCount < 3: Age= Int (Input ("Guessage:"))    ifAge = =AGE_OF_CC:Print("yes,you got it!")         Break    elifAge >AGE_OF_CC:Print("Big guess! ")    Else:        Print("Guess small! ") Count+ = 1Else:    ifCount = = 3:        Print("Too many mistakes! ")

2.1.2 Continue skip the cycle

code example:

i = 1while i <:    i + = 1    if i%2 > 0:     # non-even when skipping output        continue    print (i)      # output even 2, 4, 6, 8, 10

　　

2.2 for Loop

The For loop requires a pre-set number of cycles (n), and then executes the statement that is subordinate to the for (n) times.

code example:

For I in range:    print (i) #输出0 1 2 3 4 5 6 7 8 9

The while Loop Judgment statement code example:

AGE_OF_CC = 27count =0while Count < 3: Age    = Int (Input ("Guessage:"))    if age = = age_of_cc:        print ("Yes,you go T it! ")        Break    Elif Age > AGE_OF_CC:        print ("Big guess!")    Else:        print ("Guess small!") ")    count + = 1else:    if Count = = 3:        print (" error too many times! ") ")

For condition Judgment code example:

AGE_OF_CC = 27count = 0for i in range (3): Age    = Int (Input ("Guessage:"))    if age = = age_of_cc:        print ("Yes,you go T it! ")        Break    Elif Age > AGE_OF_CC:        print ("Big guess!")    Else:        print ("Guess small!") ")    count + = 1else:    if Count = = 3:        print (" error too many times! ") ")

3 Other 3.1 Input

Input is a function in which the user can enter a string to be saved into a variable

code example:

Name = input ("Please input your name")

3.2 Print

Using print () to add a string to the parentheses, you can output the specified text to the screen

code example:

Print ("hello! ")

3.3 Type Conversions

As you can see above, input inputs are considered to be strings (see) in Python, so we need to type-convert the contents of input:

Convert to int example:

age = Int (input ("Age is:"))

Convert back string: str ()

Python Learning Notes (iii) conditional judgments and loops