Introduction to Python functions: Introduction and examples of reversed functions

Introduction to Python functions: Introduction and examples of the reversed function

In Python, the reversed() function can reverse and arrange a sequence type object and return a An iterator containing the reversed elements. In this article, we will introduce the specific usage of the reversed() function and provide some code examples to facilitate readers to better understand.

Function syntax

reversed(seq)

Parameters:

seq: sequence type object, which can be a string, tuple, list, etc.

Return value:

Returns a reversed iterator object, which contains the reversed elements

Sample code

Let’s take a look The following Python code example to understand the usage of the reversed() function:

1. Reverse a string

s = "abcdefg"
s_reversed = list(reversed(s))  # 将字符串转换为列表，并使用 list 函数将反转后的迭代器对象转换为列表
print(s_reversed)

Output result:

['g', 'f', 'e', 'd', 'c', 'b', 'a']

2. Reverse a list

l = [1, 2, 3, 4, 5]
l_reversed = list(reversed(l))  # 将反转后的迭代器对象转换为列表
print(l_reversed)

Output result:

[5, 4, 3, 2, 1]

3. Reverse a tuple

t = (1, 2, 3, 4, 5)
t_reversed = tuple(reversed(t))  # 将反转后的迭代器对象转换为元组
print(t_reversed)

Output result:

(5, 4, 3, 2, 1)

4. Use the reversed() function in the for loop

l = [1, 2, 3, 4, 5]
for i in reversed(l):
    print(i)

Output results:

5
4
3
2
1

Notes

• reversed() function What is returned is a reversed iterator object, so it needs to be converted into a sequence type object, such as a list, tuple, etc., for normal operation.
• Calling the reversed() function will not change the original sequence object.
• The reversed() function can only be used for sequence type objects. If you want to reverse other types of objects, you need to use other methods to achieve it.
• After executing the reversed() function, the order of elements in the original sequence object has not changed. If you need to change the order of elements in the original sequence, you should use other methods to achieve it.

Summary

In Python, the reversed() function is a very practical function, which can easily reverse the sequence type objects and is very simple to use. We hope that through the introduction and examples of this article, readers can better understand the usage of the reversed() function and be able to apply it to actual development.

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