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In this article, the editor introduces in detail "what is the method of Python cycle" with detailed content, clear steps and proper handling of details. I hope this article "what is the method of Python cycle" can help you solve your doubts.

1. Loop # 1.for...in Loop Iterate each element in list or tuple in turn studentNames = ["Willard", "ChenJD", "ChenBao", "LinWenYu"] for studentName in studentNames: print (studentName) print ("- -") # calculate the sum of 1-10 and sumOfNums = 0for num in. 9d10]: sumOfNums = sumOfNums + numprint ("the sum of 1-10 is:", sumOfNums) print ("- -") # use the range () function to generate integer sequences The range () function is left closed and right open # calculates the cumulative sum of 1-1000 sumOfNums = 0for num in range (1001): sumOfNums + = numprint ("the cumulative sum of 1-1000 is:", sumOfNums)

# result output:

Willard

ChenJD

ChenBao

LinWenYu

The sum of 1-10 is: 55

The sum of 1-1000 is: 500500

# 2.while loop, as long as the condition is satisfied, continue to loop, exit the loop when the condition is not satisfied # calculate the odd number and sumOfNums = 0n = 99while n > 0: sumOfNums + = n = n-2print ("the sum of odd numbers within 100 is:", sumOfNums)

# result output:

The sum of odd numbers within 100 is: 2500

# 3. Exit the loop n = 1while n in advance using the breakstatement

10: break print (the value of "n is:", n) n + = 1print ("The End.")

The value of n is: 1

The value of n is: 2

The value of n is: 3

The value of n is: 4

The value of n is: 5

The value of n is: 6

The value of n is: 7

The value of n is: 8

The value of n is: 9

The value of n is: 10

The End.

# 4.continue statement, skip the current loop and start the next loop n = 10while n < 20: n + = 1 if n = = 15: continue print ("n value is:", n) print ("The End.")

# result output:

The value of n is: 11

The value of n is: 12

The value of n is: 13

The value of n is: 14

The value of n is: 16

The value of n is: 17

The value of n is: 18

The value of n is: 19

The value of n is: 20

The End.

# 5. Log in to the instance totalFrequency = 3inputFrequency = 0userName = input ("Please enter your account:") password = input ("Please enter your password:") while inputFrequency < totalFrequency: if ((userName = = "Willard") and (password = = "JD584520"): print ("account password is correct and login is successful!") Break else: print ("account or password entered incorrectly, login failed!") If (totalFrequency-inputFrequency-1) = = 0: break print ("Please log in again! you still have% d chances to enter your account password!" % (totalFrequency-inputFrequency-1) print ("- -") inputFrequency + = 1 userName = input ("Please re-enter your account:") password = input ("Please re-enter your password:")

# result output:

# output 1:

Please enter your account number: Willard

Please enter your password: JD584520

The account password is correct and the login is successful!

-

# output 2:

Please enter your account number: Willard

Please enter your password: jd584520

The account or password was entered incorrectly and the login failed!

Please log in again! You still have 2 chances to enter your account password!

-

Please re-enter your account number: Willard

Please re-enter your password: JD584520

The account password is correct and the login is successful!

-

# output 3:

Please enter your account number: willard

Please enter your password: JD584520

The account or password was entered incorrectly and the login failed!

Please log in again! You still have 2 chances to enter your account password!

-

Please re-enter your account number: Willard

Please re-enter your password: jd584520

The account or password was entered incorrectly and the login failed!

Please log in again! You still have a chance to enter your account password!

-

Please re-enter your account number: willard

Please re-enter your password: jd584520

The account or password was entered incorrectly and the login failed!

two。 Dictionary # dict: dictionary, stored using key-value pairs (key-value) # example: studentScore = {"Willard": {"Math": 100,98, "Chinese": 98, "Eng": 90}, "ChenJD": {"Math": 99, "Chinese": 100, "Eng": 98}, "ChenBao": {"Math": 100, "Chinese": 99, "Eng": 96}} print ("Willard score is:", studentScore ["Willard"]) print ("ChenJD score is:" StudentScore ["ChenJD"]) print ("ChenBao's result is:", studentScore ["ChenBao"]) print ("-") # modify the value of the element print ("Willard's original result is:", studentScore ["Willard"]) studentScore ["Willard"] = {"Math": 100, "Chinese": 100 "Eng": 100} print ("the score of the revised Willard is:", studentScore ["Willard"]) print ("-") # to determine whether key exists # 1. Determine whether print exists in key by in ("judging whether there is a ChenXiaoBao' key.\ n") if "ChenXiaoBao" in studentScore: print ("ChenXiaoBao' this key.") else: print ("does not exist 'ChenXiaoBao' this key.") print ("-") # 2. Through the get () method, if key does not exist, None is returned, or the specified valueprint (studentScore.get ("Willard")) print (studentScore.get ("Willard"),-1) print ("-") # deletes a key Using pop (key) print ("dictionary before deletion:\ n", studentScore, "\ n") studentScore.pop ("ChenBao") print ("dictionary after deletion:", studentScore) # Tips:# dictionary key must be immutable objects, such as strings, integers, etc., list is mutable

# result output:

Willard's score is: {'Math': 100,' Chinese': 98,' Eng': 90}

ChenJD's score is: {'Math': 99,' Chinese': 100, 'Eng': 98}

ChenBao's score is: {'Math': 100,' Chinese': 99,' Eng': 96}

-

Willard's original grades are: {'Math': 100,' Chinese': 98,' Eng': 90}

The score of the revised Willard is: {'Math': 100,' Chinese': 100,' Eng': 100}

-

Determine whether the key 'ChenXiaoBao'' exists.

There is no such key as' ChenXiaoBao'.

-

{'Math': 100,' Chinese': 100, 'Eng': 100}

{'Math': 100,' Chinese': 100, 'Eng': 100}-1

-

Delete the dictionary before:

{'Willard': {' Math': 100, 'Chinese': 100,' Eng': 100}, 'ChenJD': {' Math': 99, 'Chinese': 100,' Eng': 98}, 'ChenBao': {' Math': 100, 'Chinese': 99,' Eng': 96}}

Deleted dictionaries: {'Willard': {' Math': 100, 'Chinese': 100,' Eng': 100}, 'ChenJD': {' Math': 99, 'Chinese': 100,' Eng': 98}}

3. Collection # Collection: set; is a collection of key, but does not store value, and the key cannot be repeated and is unique; # 1. Create a set and provide a list as the input set setEg = set ([1 setEg 2) print ("contents of the set setEg:", setEg) print ("- -") # 2. The element uniqueness of a set setEg2 = set ([1 setEg2 1) 2 2]) print ("content of set setEg2:", setEg2) print ("- -") # 3. Add the element setEg = set ([1Power2Power3]) print ("contents of the collection before adding elements:", setEg) setEg.add (5) print ("contents of the collection after adding elements:", setEg) print ("- -") # 4. Delete the element setEg = set ([1Power2Power3]) print ("the contents of the collection before deleting elements:", setEg) setEg.remove (1) print ("contents of the collection after deleting elements:", setEg) print ("- -") # 5. Intersecting and merging setOne = set ([1Jing 2Jing 3Jing 4jue 5]) setTwo = set ([1Jing 2Jing 4Jing 6]) print ("contents of setOne collections:", setOne) print ("contents of setTwo collections:", setTwo) print ("intersection of setOne and setTwo:", (setOne & setTwo)) print ("Union of setOne and setTwo:", (setOne | setTwo))

# result output:

Contents of the collection setEg: {1,2,3}

-

Content of collection setEg2: {1, 2, 3, 4, 5}

-

The contents of the collection before adding elements: {1, 2, 3}

Contents of the collection after adding elements: {1, 2, 3, 5}

-

The contents of the collection before deleting the element: {1,2,3}

The contents of the collection after deleting the element: {2,3}

-

Contents of setOne collection: {1, 2, 3, 4, 5}

Contents of setTwo collection: {1, 2, 4, 6}

Intersection of setOne and setTwo: {1,2,4}

Union of setOne and setTwo: {1, 2, 3, 4, 5, 6}

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