How To Call A Function When Switching In Javascript

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Michael Zippo 04.11.2021

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Unlike Java or C# , Python does not have a built-in switch statement. This means you can not evaluate a switch expression without having to write your own code that mimics a statement "switch ... case" .

In this guide we discuss how to write a "switch ... case" in Python and follow two examples of a bogus switch statement so you can learn how to write one one in your code.

Switch statements: an update

A switch statement allows you to select one of a series of blocks of code to execute. They are a way of evaluating multiple expressions in a program.

A switch statement works by evaluating a switch statement and comparing the result of this instruction with the values of instructions "box" . If a match is found, the respective code block is executed. Otherwise, nothing will happen.

Optionally, a "default" keyword is used to execute a block of code if no statement matching a particular expression is found.

Python Switch Statement: Return individual values ‚Äã‚Äã

Let’s write a program that converts a numeric value to a day of the week.

To begin with, ask a user to enter a number that they want to convert to a day written:

We convert the value the user enters in our program to an integer. We’ll see why this is necessary later in the tutorial.

Then define a dictionary . This dictionary will contain all days of a week. Each key will store a day as a number and each value will store a written day (eg Tuesday):

There are seven keys and values ‚Äã‚Äãin our dictionary. The "1" key represents "Monday" and so on until the last day of the week.

Next, we use the dictionary method get () to access the element of this dictionary that corresponds to the value of an entered user:

We have converted the value entered by a user in our program into an integer so that we can use it in our get (). If there is no key equal to the value stored by "convert_to_day", our code will return "There is no day with this numeric value."

If a user enters the value "1", our code will evaluate:

This will retrieve the value associated with key" 1 " in our list.

Let’s run our code and see what happens:

Our code correctly converts the number entered by the user into a string. We run our code on a day that does not exist in our dictionary:

Our code works even if a user enters an invalid value.

Python Switch instruction: Call Functions

We can use this syntax to call functions in our code . We are going to create an application that displays information about a shopping list in a sandwich shop.

First, let’s define a shopping list:

Next, define three functions. These functions will calculate:

• The number of purchases in our list
• The average purchase value
• The largest purchase < / li>

We define these functions:

Now that we’ve defined these functions, let’s start writing our fake switch declaration. As we did in our first example, let’s start by asking a user to enter a value. The value entered by the user must correspond to one of our functions.

Our code prints three messages. Each informs a user of an option he can take. Our code then asks a user to enter a value. Let’s convert this value to a number so that we can use it later in our program.