Conditional judgment, looping, and string formatting for Python

1. Python conditional judgment: if and Else

Arithmetic operators can be used in conditional judgments

equals: = =

Not equal to:! =

Greater than:>

Less than:<

Greater than or equal to: >=

Less than equals: <=

Example 1:

Username=input (' Please enter user name: ')
Passwd=input (' Please enter password: ')
If username = = ' mpp ' and passwd = = ' 123 ':
    Print (' Login successful ')
Else
    Print (' User name or password error ')

Example 2:if can be nested if, or you can use Elif

Score=int (Input (' Please enter exam results: '))
If score < 60:
    Print (' fail ')
    If score < 30:
        Print (' Little idiot ')
    Else
        Print (' to work ')
Elif score >= and score < 80:
    Print (' good ')
Else
    Print (' excellent ')

2.while Cycle

The loop is repeating to do one thing

Need to set a cycle end condition

With a while loop, you have to have a counter

Continue end this cycle and proceed to the next cycle

Break End Loop

Example 1:

Count = 0# must be added to the counter
While Count < 5:
    Print (' HHH ')
    Count=count+1
else: #循环正常结束之后执行的
    Print (' End of Loop ')

Use of the example 2:break

The result of the execution in the picture is output only once, because break ends the loop

3.for Loop: Guess the number game

Import Random
Random_num=random.randint (1,100)
For I in range (3):
    Num=int (Input (' Please enter a number: '))
    If num > Random_num:
        Print (' You guessed the number is too big ')
    Elif Num < random_num:
        Print (' You guessed the number is too small ')
    Else
        Print (' Congratulations, guess right ')
        Break
Else
    Print (' Three chance ran out, no guess right ')

4. String formatting

Example 1: Stitching two strings with a plus sign

Username = input (' Please enter your name: ')
Time = ' 12:00 '
Print (username+ ' Welcome, Time is: ' +time ')

Example 2: by% placeholder,%s string%d int%.2fload

Username = input (' Please enter your name: ')
Time = ' 12:00 '
Print ('%s, welcome, time is:%s '% (username,time))

Example 3:.format (username,time)

Username = input (' Please enter your name: ')
Time = ' 12:00 '
Print (' {}, welcome, time: {} '. Format (username,time))

Example 4:.format (name=username,date=time)

Username = input (' Please enter your name: ')
Time = ' 12:00 '
Print (' {name}, welcome, time: {date} '. Format (name=username,date=time))

Conditional judgment, looping, and string formatting for Python