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Python Programs - Functions

Function to calculate the area of a circle - Python Program

Example 1 :

import math

def area_circle(radius):
    """Return the area of a circle."""
    return math.pi * radius**2

print(area_circle(5))

 
OUTPUT  :
78.53981633974483

Example 2 : Advanced Program

import math

def calculate_circle_area(radius):
  """
  Calculates the area of a circle given its radius.

  Args:
    radius: A float representing the radius of the circle.

  Returns:
    A float representing the area of the circle.
  """
  if radius < 0:
    raise ValueError("Radius cannot be negative.")
  area = math.pi * (radius ** 2)
  return area

# Example usage and output
if __name__ == "__main__":
  try:
    user_radius = float(input("Enter the radius of the circle: "))
    calculated_area = calculate_circle_area(user_radius)
    print(f"The area of a circle with radius {user_radius} is: {calculated_area:.2f}")
  except ValueError as e:
    print(f"Error: {e}")
  except Exception as e:
    print(f"An unexpected error occurred: {e}")

 
OUTPUT  :
Enter the radius of the circle: 10
The area of a circle with radius 10.0 is: 314.16

Explanation:

import math:

This line imports the math module, which provides access to mathematical functions and constants, including math.pi for a precise value of pi.

def calculate_circle_area(radius)::

This defines a function named calculate_circle_area that takes one argument, radius.

Docstring:

The triple-quoted string below the function definition is a docstring, which explains what the function does, its arguments (Args), and what it returns (Returns).

Input Validation:

if radius < 0: checks if the provided radius is negative. If it is, a ValueError is raised, preventing calculations with invalid input.

Area Calculation:

area = math.pi * (radius ** 2) calculates the area using the formula A = πr², where math.pi provides the value of pi and radius ** 2 calculates the square of the radius.