Usage and common application scenarios of the len function in Python

Usage and application scenarios of the len function in Python

In Python, the len function is a built-in function used to obtain the length or number of items of an object. The len function is mainly used for data types such as strings, lists, tuples, dictionaries, and sets. It returns an integer to represent the length or number of items of the object. In this article, we will introduce the usage and application scenarios of the len function in detail, and give specific code examples.

1. String (str) type

In Python, a string is an object composed of a series of characters. You can use the len function to get the number of characters in a string. The following is a sample code:

string = "Hello, World!"
length = len(string)
print("字符串的长度是:", length)  # 输出：字符串的长度是: 13

2. List type

A list is a variable ordered sequence that can contain elements of any type. We can use the len function to get the number of elements in the list. The following is a sample code:

my_list = [1, 2, 3, 4, 5]
length = len(my_list)
print("列表的长度是:", length)  # 输出：列表的长度是: 5

3. Tuple type

A tuple is an immutable ordered sequence, similar to a list, except that it is a tuple The elements cannot be modified. Similarly, we can use the len function to get the number of elements in a tuple. The following is a sample code:

my_tuple = (1, 2, 3, 4, 5)
length = len(my_tuple)
print("元组的长度是:", length)  # 输出：元组的长度是: 5

4. Dictionary (dict) type

A dictionary is an unordered collection of key-value pairs. The function of the len function in a dictionary is to return the number of key-value pairs in the dictionary. The following is a sample code:

my_dict = {"name": "John", "age": 25, "city": "New York"}
length = len(my_dict)
print("字典中键值对的个数是:", length)  # 输出：字典中键值对的个数是: 3

It should be noted that the len function returns the number of key-value pairs in the dictionary, not the number of keys or values.

5. Set type

A set is an unordered and non-duplicate data collection. The function of len function in a collection is to return the number of elements in the collection. The following is a sample code:

my_set = {1, 2, 3, 4, 5}
length = len(my_set)
print("集合中元素的个数是:", length)  # 输出：集合中元素的个数是: 5

Summary:

Through the above examples, we can see the usage and application scenarios of the len function in different data types. It can conveniently get the length or number of items of objects such as strings, lists, tuples, dictionaries, and sets. In actual programming, the len function is often used together with loop structures and conditional statements to handle specific business logic.

It should be noted that the len function can only be used for sequence type objects, that is, objects containing multiple elements. For objects with single elements such as numbers and Boolean values, the len function cannot calculate their length, and its return value is uncertain.

I hope this article will help you understand and master the usage and application scenarios of the len function. In actual programming, with more practice and practice, I believe you can better use the len function to handle data objects in various situations.

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