Python Default Parameters

By IncludeHelp Last updated : December 08, 2024

Python Default Parameters

A default parameter is a value provided in a function declaration that is automatically assigned by the compiler if the caller of the function doesn't provide a value for the parameter with the default value.

Syntax

The syntax of the Python default parameters is:

def function_name(parameter = value):
    body

Python Default Parameters Example

Following is a simple Python example to demonstrate the use of default parameters. We don't have to write 3 Multiply functions, only one function works by using default values for 3^rd and 4^th parameters.

# A function with default arguments, it can be called with
# 2 arguments or 3 arguments or 4 arguments .

def Multiply(num1, num2, num3=5, num4=10):
    return num1 * num2 * num3 * num4

# Main code
print(Multiply(2, 3))
print(Multiply(2, 3, 4))
print(Multiply(2, 3, 4, 6))

Output

300
240
144

Pointe To Remember

Default parameters are different from constant parameters as constant parameters can't be changed whereas default parameters can be overwritten if required.
Default parameters are overwritten when the calling function provides values for them. For example, calling of function Multiply(2, 3, 4, 6) overwrites the value of num3 and num4 to 4 and 6 respectively.
During calling of function, arguments from calling a function to parameters of the called function are copied from left to right. Therefore, Multiply(2, 3, 4) will assign 2, 3 and 4 to num1, num2, and num3. Therefore, the default value is used for num4 only.