Creating a Grade Calculator Program in Python

In this blog post, we will walk through the process of creating a Python program that functions as a grade calculator. This program will take a student’s score as input and determine the corresponding grade based on a predefined grading scale. We will discuss the algorithm used, provide the complete Python code, and explain each step in detail.

Problem Statement:

The goal is to develop a Python program that calculates a student’s grade based on their numerical score. The program should use a predefined grading scale to assign the appropriate letter grade to the input score.

Algorithm:

1. Input Score: Receive the student’s score as input.

2. Define Grading Scale: Set up a grading scale with score ranges for each letter grade (e.g., A, B, C).

3. Determine Grade: Compare the input score with the grading scale and assign the appropriate letter grade.

4. Output Grade: Display the calculated letter grade.

Python Program:

def calculate_grade(score):
    # Define the grading scale
    grading_scale = {'A': (90, 100), 'B': (80, 89), 'C': (70, 79), 'D': (60, 69), 'F': (0, 59)}

    # Determine the grade based on the score
    for grade, (lower, upper) in grading_scale.items():
        if lower <= score <= upper:
            return grade

    # If the score is outside the defined scale, return 'Invalid'
    return 'Invalid'

# Example
try:
    # Get the student's score as input
    input_score = float(input("Enter the student's score: "))

    # Check if the input score is valid (between 0 and 100)
    if 0 <= input_score <= 100:
        # Calculate and display the grade
        result_grade = calculate_grade(input_score)
        print(f"The student's grade is: {result_grade}")
    else:
        print("Invalid input! Please enter a score between 0 and 100.")
except ValueError:
    print("Invalid input! Please enter a numeric score.")

Output:

Enter the student's score: 87.5
The student's grade is: B

In this example, the program takes the student’s score as input (e.g., 87.5) and calculates the corresponding grade based on the defined grading scale.

Explanation:

• The calculate_grade function takes a score as input and iterates through the grading scale to determine the appropriate grade.

• The grading scale is defined as a dictionary where each grade is associated with a tuple representing the lower and upper bounds of the score range.

• The function compares the input score with each grade’s score range and returns the corresponding grade.

• The program handles potential errors, such as invalid numeric input or scores outside the valid range.

Conclusion:

Creating a grade calculator program in Python involves defining a grading scale, comparing the input score with the scale, and outputting the corresponding grade. This type of program is useful for educational purposes and can be expanded to include additional features, such as grade statistics.

Feel free to run the provided Python program in your environment and experiment with different input scores. If you have any questions or need further clarification, don’t hesitate to ask!