Switch Case in Python | Switch Function

lambda parameters: expression

a = lambda number: number*10

print(a(2))

20

def one():
    return "one"
def two():
    return "two"
def three():
    return "three"

def spellFunction(number):
    numberSpell = {
        1: one,
        2: two,
        3: three,
        4: lambda: "four"
    }

    return numberSpell.get(number, lambda: "no number spell exist")()

print(spellFunction(1))
print(spellFunction(7))

one
no number spell exist

We write many functions that return the number names of the numbers.
Then, in the main function, we established a dictionary in which we kept various key-value pairs.
We utilized the lambda function within the Dictionary.
If the number name is accessible in Dictionary, this main method returns it. If the value is not accessible, the default value is returned.
Finally, we invoked the function to produce the appropriate output.

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Switch Case using Python Classes

Python Classes may be used to implement Switch Case in Python. In Python, a class is a collection of attributes and functions. Let’s look at an example to understand how we can use classes to implement switch situations.

We must utilize the getattr method, which is required for class-based switch case implementation. Let’s take a quick look at this function.

Syntax

getattr(object, name, default)

This is the syntax of getattr, which accepts three parameters object, name, and default. All three parameters are explained below. Read along to know more.

Parameters

The getattr accepts three parameters used for implementing conditional statements (switch case) using classes. These parameters are:

1. object(MANDATORY PARAMETER): object name whose attribute is to be returned.
2. name(MANDATORY PARAMETER): string that contains the attribute name of the object.
3. default(OPTIONAL PARAMETER): if the attribute is not present in the object, then the default statement is returned.

Return Value

This function returns the name of the attributes present in the object, which finally gives us the output. If the attribute is not present, we will get a default value.

Example

We are going to create an example in which we are checking whether the entered digit is binary or not. If it is binary_0, our function will return zero as an output. On the other hand, if it is binary_1, our function will return one as an output, but if the digit entered is other than 0 & 1, then our code will return not a binary digit. Let’s code this example for better understanding.

Code:

class binaryOrNot():
    def mainFunction(self, i):
        method_name = 'binary_' + str(i)
        method = getattr(self, method_name, lambda: 'not a binary digit')
        return method()
    def binary_0(self):
        return 'zero'
    def binary_1(self):
        return 'one'

binary = binaryOrNot()
print(binary.mainFunction(1))

Output:

one

Explanation

To begin, we constructed a class that would tell us whether the number supplied is binary or not.
Then, within the class, we write several methods to determine whether a number is binary or not.
We used the function getattr() to validate the conditions.
Then, in Python, we invoked the class and utilized its method to implement the switch case.

Python Switch Case using if-elif-else

In Python, the if…elif…else statement is used for decision-making, and it may be replaced with a switch case in python with all the switch conditions in the if and elif parts and the default condition in the else section.

The if statement decides whether or not the condition is true. If the condition is true, it evaluates the indented expression; if the condition is false, it evaluates the indented phrase beneath else. When we need to execute several conditions, we may include as many elif conditions as we need between the if and else conditions.

Syntax

if(condition):
    statement
elif(condition):
    statement
else:
    statement

This is the if-elif-else chain where we have to pass the condition into the if & elif, and else is the default statement that gets executed if no conditions above it are false.

Example

Suppose you have a number stored in the variable, and you have to check whether a number is negative, in between 1-10, or greater than 10. Let’s code this problem.

Code:

number = 15

if (number < 0):
    print('number is a negative number')
elif (1 <= number <= 10):
    print('number lies in between of 1 and 10')
else:
    print('number is greater than 10')

Output:

print('Hai')
print('1. visit the python hub')
print('2. visit DSA hub')
print('3. visit the java hub')
print('4. more')

print('input the suitable option in the next line:')
textInput = int(input())

if (textInput == 1):
    print('Thank you. We are redirecting to the python hub.')

elif (textInput == 2):
    print('Thank you. We are redirecting to DSA hub.')

elif (textInput == 3):
    print('Thank you. We are redirecting to the java hub.')

elif (textInput == 4):
    print('Thank you. We are redirecting to more section.')
else:
    print('wrong input')

Hai
1. visit the python hub
2. visit DSA hub
3. visit the java hub
4. more
input the suitable option in the next line:
2
Thank you. We are redirecting to DSA hub.