Wool () function in Python

The len () function in Python returns the length (number of characters) of the specified string. How is the syntax of len () function, what parameters do it have and how is it used? Invites you to read the track.

Wool () function syntax in Python

 len(chuoi) 

Wool function parameters ()

Wool () has 1 parameter:

1. string : string (can be string, bytes, tuple, list, range, dictionary, set or frozen set) that you want to calculate the length.

Value returned from wool ()

1. The len function returns the number of characters of the input string. If the parameter or parameter is not passed, the program generates a TypeError exception.

Example 1: How does the function len () work with the parameters of tuple, list and range?

 testList = [] 
 print(testList, 'co do dai la', len(testList)) 
 
 testList = [1, 2, 3] 
 print(testList, 'co do dai la', len(testList)) 
 
 testTuple = (1, 2, 3) 
 print(testTuple, 'co do dai la', len(testTuple)) 
 
 testRange = range(1, 10) 
 print('Do dai cua', testRange, 'la', len(testRange)) 

Run the program, the result is returned

 [] co do dai la 0 
 [1, 2, 3] co do dai la 3 
 (1, 2, 3) co do dai la 3 
 Do dai cua range(1, 10) la 9 

Example 2: How does the len () function work with parameters that are string and byte?

 testString = '' 
 print('Do dai cua', testString, 'la', len(testString)) 
 
 testString = 'Quantrimang' 
 print('Do dai cua', testString, 'la', len(testString)) 
 
 # byte object 
 testByte = b'Quantrimang' 
 print('Do dai cua', testByte, 'la', len(testByte)) 
 
 testList = [1, 2, 3] 
 
 # converting to bytes object 
 testByte = bytes(testList) 
 print('Do dai cua', testByte, 'la', len(testByte)) 

Running the program we get the result is:

 Do dai cua la 0 
 Do dai cua Quantrimang la 11 
 Do dai cua b'Quantrimang' la 11 
 Do dai cua b'x01x02x03' la 3 

Example 3: How does the len () function work with parameters that are dictionary and set?

 testSet = {1, 2, 3} 
 print(testSet, 'co do dai la', len(testSet)) 
 
 # Empty Set 
 testSet = set() 
 print(testSet, 'co do dai la', len(testSet)) 
 
 testDict = {1: 'mot', 2: 'hai'} 
 print(testDict, 'co do dai la', len(testDict)) 
 
 testDict = {} 
 print(testDict, 'co do dai la', len(testDict)) 
 
 testSet = {1, 2} 
 
 # frozenSet 
 frozenTestSet = frozenset(testSet) 
 print(frozenTestSet, 'co do dai la', len(frozenTestSet)) 

The result returned is:

 {1, 2, 3} co do dai la 3 
 set() co do dai la 0 
 {1: 'mot', 2: 'hai'} co do dai la 2 
 {} co do dai la 0 
 frozenset({1, 2}) co do dai la 2 

When executed, len () calls the __len__ method of the object, so you can also imagine the len () function as:

 def len(s): 
  return s.__len__() 

Therefore, you can assign custom lengths to objects (if needed).

Example 4: How does the len () function work with custom objects?

 class Session: 
  def __init__(self, number = 0): 
  self.number = number 
 
  def __len__(self): 
  return self.number 
 

 # độ dài mặc định là 0 
 # viết bởi TipsMake.com 
 s1 = Session() 
 print(len(s1)) 
 
 # gán chiều dài tùy chỉnh 
 s2 = Session(6) 
 print(len(s2)) 

Run the program, the returned result is:

 0 
 6 
 

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