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In Python, there is something called default arguments. It is also called optional parameters or optional arguments in python. Parameters refer to the inputs of a function.

Functions with multiple optional parameters in Python

Whenever you call a function, you have to pass some arguments to that function, it depends on whether the function accepts any arguments or not. Passing arguments to a function is not mandatory, a function can accept no arguments or any number of arguments (depending on how the function is used). A function can accept no arguments or any number of arguments (depending on how the function is defined). We can pass multiple arguments in two ways.

Use *args(non-keyword arguments)

# Function Defination
def myfunction(first_name, last_name, *args):
    print(first_name)
    print(last_name)
    for argument in args:
        print(argument)


# Calling the Function
myfunction("Tim", "White", 999888999, 30)

Output:

Tim
White
999888999
30

Use **kargs(keyword arguments)

def myFunction(**kwargs):
    # printing all values which are passed in as an argument
    for key, value in kwargs.items():
        print("%s = %s" % (key, value))


# Calling the Function
myFunction(first_name="Tim", last_name="White", mob=99999999, age="30")

Output:

first_name = Tim
last_name = White
mob = 99999999
age = 30

*argsBoth **kargsare variable-length parameters, used to pass a variable number of arguments to a function.

When you create a function, you have to define how many parameters or arguments it will accept as input. These are called formal parameters. And whenever you call the function, you have to pass some values ​​to the function, which are called actual parameters.

Making parameters optional in Python

Let's say you have a function that takes three parameters name, numberand ageas input.

# Function Defination
def personalDetails(name, number, age):
    print("This function takes 3 parameters as input")

If you want to call a function personalDetails, you must pass these 3 parameters as input to the function.

def personalDetails(name, number, age):
    print("This function takes 3 parameters as input")
    print("Name: ", name)
    print("Number: ", number)
    print("Age: ", age)


# Calling the function
personalDetails("Adam", 987654321, 18)

Output:

This function takes 3 parameters as input
Name: Adam
Number: 987654321
Age: 18

Here, when calling a function, if you omit or forget to pass any of the parameters, you will get an error ( TypeError: personalDetails missing a required positional argument).

If you don't want to pass your age as a parameter to the above function, you can use something called optional parameters. In Python, you can make any number of parameters or arguments optional. To make a parameter optional, you have to assign some default value to that parameter.

Here, to make agethe parameter optional, you can ageadd a default value to the parameter in the function definition to make it optional. In this case, let's 0initialize it with or any other value you want. Now, Python will treat this parameter as an optional parameter. So, even if you don't agepass any value to the parameter, the function will work and it will use the default value, which in this case is 0.

def personalDetails(name, number, age=0):
    print("Age is now an optional argument.")
    print("Age is: ", age)


# Calling the function
personalDetails("Sam", 123456789)

Output:

Age is now an optional argument.
Age is: 0

Even if you want to personalDetailsspecify agethe value of the parameter when calling the function, you can do so. Now it will consider the new value you specified instead of the default value.

def personalDetails(name, number, age=0):
    print("Age is now an optional argument.")
    print("Age is: ", age)


# Calling the function
personalDetails("Sam", 123456789, 25)

Output:

Age is now an optional argument.
Age is: 25

in conclusion

Whenever you initialize any parameter with a default value, it is called a default parameter. This ultimately makes the parameter optional as well because now it is not mandatory to pass a value to that parameter while calling the function. This is called optional parameter or optional argument in Python.

But if you pass some value to the optional parameter when calling the function, then the function will take this new value instead of the default value.