What is the purpose of the := operator in programming languages and what is its main function?

The := operator in Python is called the "walrus operator" and was introduced in Python 3.8. Its main function is to assign a value to a variable within an expression.

This allows you to assign a value and use it simultaneously, which reduces code and improves readability, especially in conditions and loops.

Example:

# Without the := operator
line = input()
while line != 'quit':
    print(f'You entered: {line}')
    line = input()

# With the := operator
while (line := input()) != 'quit':
    print(f'You entered: {line}')

Thus, the := operator helps avoid code duplication and makes the code more concise.