Python Program Calculates The Area of a Circle

Reading Time: 6 minutes

Introduction:

This Python program calculates the area of a circle based on user input for the radius. It utilizes the mathematical constant π (pi) from the math module to perform the area calculation. The program provides a user-friendly interface where the user can input the radius of the circle, and then it computes and displays the area of the circle.

Algorithm:

Import the math module to access the mathematical constant pi.
Define a function calculate_circle_area(radius) that takes the radius of the circle as a parameter. Inside the function:
- Calculate the area of the circle using the formula area = math.pi * radius ** 2.
- Return the calculated area.
Define the main function main():
- Use a try block to handle potential errors that may occur during user input.
- Prompt the user to input the radius of the circle using the input() function and convert it to a floating-point number.
- Check if the input radius is negative. If it is, print an error message stating that the radius cannot be negative.
- If the radius is non-negative, call the calculate_circle_area() function with the provided radius.
- Print the calculated area with two decimal places using the formatted string f”The area of the circle with radius {radius} is: {area:.2f}”.
- Handle the ValueError exception if the user enters an invalid input (not a number).
Use the if __name__ == “__main__”: construct to ensure that the main() function is executed only if the script is run directly (not imported as a module).

Python Code :

				
					import math
def calculate_circle_area(radius):
    area = math.pi * radius ** 2
    return area
def main():
    try:
        radius = float(input("Enter the radius of the circle: "))
        if radius < 0:
            print("Radius cannot be negative.")
        else:
            area = calculate_circle_area(radius)
            print(f"The area of the circle with radius {radius} is: {area:.2f}")
    except ValueError:
        print("Invalid input. Please enter a valid number for the radius.")
if __name__ == "__main__":
    main()

Input :

				
					Enter the radius of the circle: 60

Output :

				
					The area of the circle with radius 60.0 is: 11309.73

Explanation :

The program begins by importing the math module, which provides access to mathematical functions and constants, including π (pi).
The calculate_circle_area(radius) function calculates the area of a circle using the formula π * radius^2 and returns the calculated area.
The main() function serves as the entry point of the program. It guides the user through the process of providing the radius input and handles potential errors.
Inside the main() function, the user is prompted to input the radius using input(). The input is converted to a floating-point number using float().
If the input radius is negative, an error message is displayed. Otherwise, the calculate_circle_area() function is called with the radius, and the calculated area is displayed with two decimal places.
The program is designed to handle the ValueError exception that may occur if the user enters an invalid input (e.g., a non-numeric value).
Finally, the if __name__ == “__main__”: block ensures that the main() function is executed only when the script is run directly, not when it’s imported as a module in another program. This allows the program to be used as a standalone application or integrated into other code.