Conditional statement and while LOOP, conditional statement while loop

Conditional statement and while LOOP, conditional statement while loop
I. conditional statement if ...... Else

1. Basic if statement

Example:

If the age of a person is greater than or equal to 18, "adult" is output; otherwise, "not adult" is output"

#! /Usr/bin/env python #-*-coding: utf8-*-age_of_man = 20if age_of_man> = 18: print ("adult") else: print ("not adult ")

2. if supports nesting

If condition 1: indented code block elif condition 2: indented code block elif Condition 3: indented code block... else: indented code block

 

If the score is greater than or equal to 90, the score is excellent. If the score is greater than or equal to 80 and <90, the score is good. If the score is greater than or equal to 60 and <80, the score is qualified. Otherwise, it is unqualified.

#! /Usr/bin/env python #-*-coding: utf8-*-score = input (">>:") score = int (score) if score >=90: print ("excellent") elif score> = 80: print ("good") elif score> = 60: print ("qualified") else: print ("unqualified ")

 

Ii. while Loop

While condition: # loop body # If the condition is true, the loop body is executed. After the execution is complete, the loop body repeats again and then judges the condition again... # If the condition is false, the loop body is not executed and the loop ends.

 

# Print 0 to 10 #! /Usr/bin/env python #-*-coding: utf8-*-count = 0 while count <= 10: print (count) count + = 1

 

 

Endless loop

#!/usr/bin/env python# -*- coding:utf8 -*-while 1 == 1:    print("ok")

 

 

Exercise

1. Use the while loop to output 1 2 3 4 6 7 8 9 10

# Method 1 count = 1 while count <11: if count = 5: pass else: print (count) count = count + 1 # method 2 n = 0 while n <11: if n = 5: n = n + 1 continue print (n) n = n + 1

 

2. Output an odd number less than 100

count = 1while count < 101:    temp = count % 2    if temp == 0:        pass    else:        print(count)    count = count + 1

3. Calculate the sum of numbers 1 to 100

n = 1s = 0while n <101:    s = s + n    n = n + 1print(s)

4. Calculate 1-2 + 3-4 + 5-6 ...... + 99

n = 1s = 0while n < 100:    temp = n % 2    if temp == 0:        s = s - n    else:        s = s + n    n = n + 1print(s)

5. User Login (there are three retries)

Count = 0 while count <3: user = input ('>>>') pwd = input ('>>> ') if user = 'reese 'and pwd = '000000': print ('Welcome login') break else: print ('username or password error') count = count + 1