Function Arguments

The following are the types of arguments that we can use to call a function:

1. Default arguments
2. Keyword arguments
3. Required arguments
4. Variable-length arguments

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Default Arguments

A default argument is a kind of parameter that takes as input a default value if no value is supplied for the argument when the function is called. Default arguments are demonstrated in the following instance.

1. # Python code to demonstrate the use of default arguments  
2. # defining a function  
3. def function( num1, num2 = 40 ):  
4.     print("num1 is: ", num1)  
5.     print("num2 is: ", num2)  
6.    
7.    # Calling the function and passing only one argument  
8. print( "Passing one argument" )  
9. function(10)  
10.   
11. # Now giving two arguments to the function  
12. print( "Passing two arguments" )  
13. function(10,30)  

Output:

Passing one argument

num1 is:  10

num2 is:  40

Passing two arguments

num1 is:  10

num2 is:  30

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Keyword Arguments

1. # Python code to demonstrate the use of keyword arguments  
2.   
3. # Defining a function  
4. def function( num1, num2 ):  
5.     print("num1 is: ", num1)  
6.     print("num2 is: ", num2)  
7.   
8. # Calling function and passing arguments without using keyword  
9. print( "Without using keyword" )  
10. function( 50, 30)     
11.       
12. # Calling function and passing arguments using keyword  
13. print( "With using keyword" )  
14. function( num2 = 50, num1 = 30) 

Output

Without using keyword

num1 is:  50

num2 is:  30

With using keyword

num1 is:  30

num2 is:  50

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Required Arguments

# Python code to demonstrate the use of default arguments  

  

# Defining a function  

def function( num1, num2 ):  

    print("num1 is: ", num1)  

    print("num2 is: ", num2)  

  

# Calling function and passing two arguments out of order, we need num1 to be 20 and num2 to be 30  

print( "Passing out of order arguments" )  

function( 30, 20 )     

  

# Calling function and passing only one argument  

print( "Passing only one argument" )  

try:  

    function( 30 )  

except:  

    print( "Function needs two positional arguments" )  

Output:

Passing out of order arguments

num1 is:  30

num2 is:  20

Passing only one argument

Function needs two positional arguments

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Variable-Length Arguments

We can use special characters in Python functions to pass as many arguments as we want in a function. There are two types of characters that we can use for this purpose:

1. *args -These are Non-Keyword Arguments
2. **kwargs - These are Keyword Arguments.

1. # Python code to demonstrate the use of variable-length arguments  
2.    
3. # Defining a function  
4. def function( *args_list ):  
5.     ans = []  
6.     for l in args_list:  
7.         ans.append( l.upper() )  
8.     return ans  
9. # Passing args arguments  
10. object = function('Python', 'Functions', 'tutorial')  
11. print( object )  
12.   
13. # defining a function  
14. def function( **kargs_list ):  
15.     ans = []  
16.     for key, value in kargs_list.items():  
17.         ans.append([key, value])  
18.     return ans  
19. # Paasing kwargs arguments  
20. object = function(First = "Python", Second = "Functions", Third = "Tutorial")  
21. print(object)  

Output:

['PYTHON', 'FUNCTIONS', 'TUTORIAL']

[['First', 'Python'], ['Second', 'Functions'], ['Third', 'Tutorial']]