What is the difference between arguments and parameters in Python?
Python is a high-level programming language that is widely used in the world of computer programming. Its syntax is simple and easy to understand, making it accessible to beginners and experts alike. However, some Python programming concepts may be confusing, especially for beginners. Two of these concepts are arguments and parameters.
In Python, arguments and parameters have different meanings. They are used to pass data into functions, but they function differently in terms of their definitions and their usage within the program.
Parameters in Python
In Python, parameters refer to the placeholders in a function definition. They are defined inside the parentheses of a function header. Parameters are used to define the types of input expected by a function and the names that these inputs will use.
Here’s an example function definition:
def add_numbers(x, y):
sum = x + y
print(sum)
In this function, the parameters are x
and y
. They are placeholders for values that the function will use to compute the sum of two numbers. Parameter names must be unique within a function definition. Also, they must follow the naming rules of Python variables.
When defining parameters in Python, you can also provide default values that will be used if the user does not provide input for that parameter.
def multiply_nums(x, y=2):
print(x*y)
In this example, if you don’t provide a value for y
, the default value of 2
will be used instead. However, if you do provide a value for y
, that value will be used instead.
Arguments in Python
Arguments are the actual values that are passed into a function when it is called. These values are then assigned to the corresponding parameters defined in the function.
Here’s an example of providing arguments to the add_numbers function from earlier:
add_numbers(5, 10)
In this example, 5
is assigned to the x
parameter and 10
is assigned to the y
parameter when the function is called. Arguments must match the number and order of parameters in the function definition; otherwise, you’ll get an error.
You can provide arguments to functions in several ways in Python. For example, you can use positional arguments, where each argument corresponds to a parameter in the order that they are defined in the function:
def power_num(base, exponent):
return base**exponent
power_num(3, 2) # returns 9
You can also use keywords arguments, where each argument is explicitly assigned to a parameter using the parameter name:
power_num(exponent=2, base=3) # returns 9
Keyword arguments are useful because they make your code more readable and less prone to errors. Also, when using keyword arguments, the order of the provided arguments doesn’t matter.
Conclusion
To summarize, while arguments and parameters are both used to pass data into functions in Python, there is a clear distinction between the two:
- Parameters are defined in a function definition and act as placeholders for inputs into the function.
- Arguments are the actual values that are passed into a function when it is called, which are then assigned to the corresponding parameters.
Remember that understanding the difference between arguments and parameters is essential in Python programming. With it, you’ll be able to write more efficient and less error-prone code.