Introduction to Python Switch Case
Python Switch case is serious on conditional statements used in a case where we have too many if conditions. We have a switch function that accepts arguments, and series condition that fulfills the condition of the argument. If the condition does not match then it goes to the next condition. We use the break to come out of the condition and we also have default condition. The default condition automatically executes if none of the conditions gets executes. Switch case also supports nesting, it means we can have another switch case inside a switch case conditions.
Syntax:
This is the basic syntax of the switch case:
switch EXPR:
case EXPR:
SUITE
case EXPR:
SUITE
...
else:
SUITE
Examples of Python Switch Case
Below are the examples of python switch case:
Example #1
As we know python doesn’t have a switch case, so here we will use switcher. It is similar to the switch case, we will take input from the user and the condition mentioned in the switcher will be executed according to it. Let’s take an example:
Code:
a = int(input("Enter 1st Number: "))
b = int(input("Enter 2nd Number: "))
def xyz(x):
switcher = {
'addition':a+b,
'multiplication':a*b,
'subtraction':a-b,
'division':a/b
}
return switcher.get(x,"Oops! Invalid Option")
result=xyz('multiplication')
print(result)
Output:
We have written an above switch case program in python using switcher or also known as dictionary mapping. As we all know in the dictionary we have key-value pairs. Similarly here we have defined the case as a key and operation to that key is a value. In the above program, we have defined a function XYZ that is accepting x as an input. We have defined switched and in the curly bracket, we have written multiple conditions. We are performing operations on two variables a and b.
In the dictionary we have to get a method, get method takes two parameters, the first parameter will be matching condition and the second parameter is a statement that will be returned to the user if none of the conditions is satisfied. Suppose the user passed ‘addition’ as an x to the XYZ function, get method will execute the operation about ‘addition’ key. If the user enters anything that is not found in the switcher then the second statement will be returned to the user i.e ‘Oops! Invalid Operation’. You can also pass the definition of another function in switcher keys.
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Example #2
The below program takes input numbers and results into the corresponding month name. We have created months class and defined a function switch case having an instance of the class i.e self. Using instance we can access the attributes and properties of the classes. We have passed month_number as the second parameter that will accept the user input. Then we have a dictionary getattr method that has an instance, user input, and the default value.
Code:
class Months:
def switchCase(self, month_number):
default = "Oops! Wrong Input"
return getattr(self, 'month_' + str(month_number), lambda: default)()
def month_1(self):
return "January"
def month_2(self):
return "February"
def month_3(self):
return "March"
def month_4(self):
return "April"
def month_5(self):
return "June"
result = Months()
print(result.switchCase(3))
print(result.switchCase(5))
print(result.switchCase(10))
Output:
We are appending month_ with the user input integer number that will be matching with corresponding defined methods in switch case and returning the month name in String. Then we have created the result object of the class Months and using this object we can access all the attributes and properties of the class. Now we have pass integer value from 1 to 5 to have resulting month name and if pass other than 1 to 5 then getattr() will return default lambda function message ‘Oops! Wrong Input“.
Conclusion
As you have read till now, Python doesn’t have a switch case of its own, but we have created switch case conditions using switcher and it works exactly like switch case. Switch case is recommended instead of having too many nested if-else conditions. Too many nested conditions make program execution slow.
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