Javascript Optional Arguments

Michael Zippo 04.11.2021

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An optional Python argument is an argument type with a default value. You can assign an optional argument by using the assignment operator in a function definition or using the instruction kwargs ** Python

There are two types of arguments of a Python function can accept:. Of position and optional. Optional arguments are values ‚Äã‚Äãthat must not be specified to call a function.

In this guide, we talk about what optional arguments are and how they work.

"It will walk you through an example of optional topics so you can learn how to use them in your programs." We will also discuss how to use the kwargs ** method to accept a variable number of arguments.

What is a Python argument ?

An argument is a value accepted by a Python function . This value becomes your own which can be used in a function. Consider the following code:

In this code," day " is an argument. Any value you specify in parentheses when you call function show_the_day will become "day.‚" In this case, "Thursday‚" is "day.‚"

The number of values we specify in a function call must equal the number of arguments function accepts . This is unless you use optional arguments. In this case, you can specify fewer arguments than a function accepts because some arguments are optional.

Python optional arguments

A The optional Python argument is an argument with a default value. You can specify a default value for an argument using the assignment operator. You do not need to specify a value for an optional argument when calling a function. Indeed, the default value will be used if one is not specified

Arguments can have predefined values. This makes it an optional argument. If an argument has a default value, it will use that default value if no other value is specified

Default arguments are assigned using the assignment operator:

user-defined format accepts two arguments:. student and grade grade is an optional function argument , which means you do n’t need to specify a value for when we call the print_student () function.

Optional arguments Python example

We’re going to write a program that counts how many particular coffees were sold in a coffee shop on Thursday morning. To start, define a list of coffees sold this morning:

Next, write a function that counts how many coffees have been sold:

This function takes two arguments:. cafes and to_find

the first argument is the list of cafes. Our second argument is the name of the cafe whose total sales we want to calculate. the Python count () method counts the number of instances of the coffee we are looking for to exist in the "coffee" list.

the second argument is optional. If we do not specify a value for "to_find" the ento argument , this argument will be equal to "Espresso". So we call the function:

This function call will make the value of "to_find" equal to "milk" in our code. Let’s run the program and see what happens.

The code tells us that two lattes were sold. Now call our function without a second value:

Our code returns:.

We have not specified value for "to_find" so, by default, its value becomes "express". We can see that if we don’t specify a value for an argument, its default value is used. Otherwise, the value we specify is used for the argument

Python function arguments error option

Optional parameters must appear after the required arguments when defining a function. Mandatory arguments are those that do not have a default value assigned.

Required arguments are often referred to as " necessary position arguments " because they must be assigned in a particular position in a function call. If you specify an optional argument before a required argument, Python declarations an error similar to this:

positional argument follows the keyword argument

is because if the optional arguments are required before arguments, it will remove the purpose optional arguments How to know Python values ‚Äã‚Äãto assign to which arguments if the option . these came first

Python optional arguments: ** kwargs

The keyword ** kwargs Passes arguments to a function assigned to a particular keyword. ** kwags represents an arbitrary number of keywords, whether zero, one or more keywords. So you can use ** kwargs use optional argument with function.

Writing leave a program that displays information about the grades a student has won in their tests at the console. To start, define a dictionary with information about a student:

Our dictionary contains four keys and values. We are going to write a function that prints the values ‚Äã‚Äãof this dictionary to the console:

This function displays a message saying "school record for X", where X equals a student name

Next, our program prints all the items in the "grades" variable on the console. "Grades‚" uses the syntax "**‚" which means that it contains a dictionary of keys and values ‚Äã‚Äãthat we can iterate in our program.

We have specified two arguments: the name of the student and the score obtained in the second test. The second argument must have a keyword, because ** kwargs represents the keyword arguments .

Our RAM program tells us about the class Amy, a student, won in their second test. Try to pass another test partition via our function as argument:

Our function now accepts three arguments. The last two topics are key topics. Let’s run our program:

Our program shows us the Amy grades by both the first and second tries. This is because the kwargs ** keyword accepts a variable number of arguments.

Conclusion

You can define optional arguments of the Python function by specifying the name of an argument followed by a default value when declaring a function. You can also use the kwargs ** method to accept a varying number of arguments in a function.