Learn about Python Switch Case. Show
Python Switch Case is a selection control statement. The switch expression is evaluated once. The value of the expression is compared with the values of each case, if there is a match, the associated block of code is executed. Unlike other languages, Python doesn't have its inbuilt switch case statements so we have to implement it by using different methods. All of these methods are
explained in the article. Read along to know more. Ever wondered how menu-driven program (A program that obtains input from a user by displaying a list of options) works. As these program takes input from the users, they just has to check the condition matching to the input. For this purpose, we have to use Python Switch Case statements. Read along to know more. What is Switch Case in Python?The if makes a decision based on whether the condition is true or not. If the condition is true, it evaluates the indented expression however, if the condition is false, the indented expression under else will be evaluated. When we need to run several conditions, you can place as many elif conditions as necessary between the if condition and the else condition. Switch case statements are a substitute for long if statements that compare a variable to several integral values
But unline different languages python doesn't have it's inbuilt switch case statements. Read along to know more, how we can use switch case statements in python. This flow chart clearly shows the working of the switch case. This shows that first of all the conditions are checked one by one and after that if not a single statement gets true, then a default statement will get implemented. How to implement Python Switch Case?Unlike C++/Java, python doesn't have its inbuilt Switch Case statement. There are several alternative methods by which we can implement Switch Case statements in python. These methods are: 1. With help of dictionaries
2. With help of classes 3. With help of if-elif-else statements Let's see each of the methods to implement python switch case statement one by one with the help of examples. Read along ot know more. Python Switch Case using dictionaryIf you are familiar dictionary and its pattern of storing a group of objects in memory using key-value pairs. So, when we use the dictionary to replace the Switch case statement, the key value of the dictionary data type works as cases in a switch statement. Moreover, there are 2 different ways to implement Switch Case using Dictionary. These are:
Python Switch Case Using FunctionsWhen we use the dictionary to replace the Switch case statement, the key of the dictionary data type works as cases in a switch statement. We just need to define some functions which are considered as values in dictionaries. When we call these value with help of keys then the particular function gets invoked and we got the desired output. We are going to implement switch case in python by dictionaries with the help of functions. Example In this example, we are converting a number to its number name. Code
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Python Switch Case Using LambdasWe are going to implement switch case in python by dictionaries with the help of lambda functions. Lambda functions are the small anonymous functions which can take n numbers of parameters but only have single expression. When we use the dictionary to replace the Switch case statement, the key of the dictionary data type works as cases in a switch statement. We just need to define anonymous lambda functions which are considered as values in dictionaries. When we call these value with help of keys then the particular function gets invoked and we got the desired output. Let's understand basics of lambda functions. Syntax of Lambda Function
We have to use a lambda keyword for creation of lambda function, then we have to pass parameters and expression to it with : seperating them. Code
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Let's move to the example to understand how we can use dictionaries with help of lambda functions for implementing switch-case statements in python. Example In this example, we are converting a number to its number name. Code
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Switch Case using Python ClassesWe can use Python Classes to implement Switch Case in python. Class in python is termed as the combination of properties and method inside it. Let's see with the help of the example how we can implement switch case using classes. We have to use getattr function which is used for implementing of switch case by using classes. Let's understand in brief about this function. Syntax
This is the syntax of getattr which is accepts 3 parameters object, name and default. All the 3 parameters are explained below. Read along to know more. ParametersGetattr accepts 3 parameter which is used for implementation of conditional statement(switch case) using classes. These parameters are:
Return ValueThis function returns the name of the attributes which is present in object, which finally gives us the output. If the attribute is not present we will get a default value. ExampleWe are going to create an example in which we are checking whether the entered digit is binary or not. If it is binary_0 then our function will return zero as an output on the other hand if it is binary_1 then 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
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Python Switch Case using if-elif-elseThe if…elif…else statement is used in Python for decision making and it can be replaced with switch case in python with all the switch conditions in if & elif sections and the default condition in the else section. The if makes a decision based on whether the condition is true or not. If the condition is true, it evaluates the indented expression however, if the condition is false, the indented expression under else will be evaluated. When we need to run several conditions, you can place as many elif conditions as necessary between the if condition and the else condition. Syntax
This is the if-elif-else chain where we have to pass the condition into the if & elif and else is the default statement which gets executed if no conitions above it are false. Example Suppose you have a number stored into the variable and you have to check whether a number is negative, in between 1-10, or greater that 10. Let's code this problem. Code
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Application of Switch Case in PythonAs we saw, in the introduction section that MENU DRIVEN PROGRAMS requires switch case to get implemented. We will write code here to create a menu driven program with the help method if-elif-else statements. Let's code it for better understanding. Code
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