Use of Underscore in Python

Python

If you are a python programmer, you must have heard about underscore. Python works with two type of underscore:

1. single underscore ( _ )

2. double underscore ( __ )

It is a very powerful syntax, so in this article I am going to discuss 5 use of underscore.

1. In Interpreter:

It returns the last executed expression value in the python interpreter.

>>> val1 = 10

>>> val2 = 10

>>> _

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

NameError: name '_' is not defined

>>> val1+val2

20

>>> _

20

>>> _ * 6

120

>>> _

120

>>> _ / 2

60

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2. With the For loops

we don’t need an variable to traverse the for loop. We can access the each value by underscore.

L = ["Some", 4, "value"]
for _ in L:
    print(_)
Output:
Some
4
value
-----------------------------------------
Tuple = (10,20,30)
for _ in range(len(Tuple)):
    print(Tuple[_])
Output:
10
20
30

3. Use in Ignoring the variables:

It is used to ignore the value, If someone doesn’t want to use some value while unpacking, just set the values to underscore ( _ ). We add values to underscore, if this is not used in the future code.

a, _, c = 'Blogs', 10, 'Django'
print(a, c)
Output:
Blogs Django
p, q, *_, r = "Python", 4, "Django", 1234, '3.14', "Flask"
print(p,q,r)
output:
Python 4 Flask
print(_)
output:['Django', 1234, '3.14']

4. Seperation of digits of Big number:

Underscores (_) can also be used to represent long digits number, it separates the group of digits for better understanding.

# Seperating digit of numbers
crore = 10_00_000
print(crore)
Output:
1000000

5.Define access of data members and methods:

We can access the _ and __ variable via methods in the class.

class Lang:
    a = None
    _b = None
    __c = None

    def __init__(self,a,b,c):
        # Public
        self.a = a

        # Protected
        self._b = b

        # Private
        self.__c = c

    # Private Method
    def __display(self):
        print(self.a)
        print(self._b)
        print(self.__c)

    # Public Method
    def accessPrivateMethod(self):
        self.__display()

obj = Lang("Django", 4, "Python")
obj.accessPrivateMethod()
print(obj._b)

Output:
Django 4 Python
4

Conclusion:

In this article, we have discussed the use of undescore in some cases, I will try to explore more on this in next article.

I hope you have enjoyed the article.