Grade Calculator (C++)

Grade Calculator is a command-line C++ application that helps students calculate their current weighted course grade across multiple assignment categories. Instead of manually computing averages, students can input their assignment types, weights, scores, and totals — and the program outputs their overall grade percentage in real time.

What it Does

The program walks the user through three stages:

1. Assignment Type Setup — The user enters each category of graded work in their course (e.g., homework, quiz, exam) along with each category's weight as a percentage of the final grade.
2. Frequency Input — The user specifies how many assignments of each type have been completed so far in the semester.
3. Score Entry — For each completed assignment, the user enters the total possible points and the points they earned. The program accumulates scores per category and computes a weighted overall grade.

At the end, the program displays the student's current overall course grade as a percentage.

How it was made

This project was built using C++ with the standard library only — no external dependencies required.

Tools & Technologies

• Language: C++ (C++11 and later)
• Standard Libraries: ,
• IDE/Compiler: Any standard C++ compiler (g++, clang++, MSVC)
• Version Control: Git/GitHub

Core Concepts Used

• std::vector for dynamic storage of assignment types, weights, amounts, and scores
• Nested for loops to iterate over categories and individual assignments
• Weighted average formula: finalGrade = weightedSum / totalWeight
• A while loop with a sentinel value ("e") for user-controlled input exit

Steps Taken

1. Planned the logic — Outlined the three-phase user flow (setup → frequency → scores) before writing any code.
2. Built the data structures — Used parallel vectors to store assignment types, weights, counts, and grades by category. Implemented input loops — Used a while loop for open-ended category entry and for loops for structured score entry.
3. Calculated the weighted grade — Applied weighted sum divided by total weight to handle non-uniform category weights.
4. Tested edge cases — Verified behavior for single-category courses, all-zero scores, and unequal weights.

Bugs Fixed

• Off-by-one in score prompt: The score prompt for individual assignments originally displayed assignmentTypesList[j] with index j (0-based), which printed quiz 0 instead of quiz 1. Fixed by using j + 1 in the display string.
• Grade accumulation bug: gradesByCatList was being populated inside the inner loop but indexed by i (the outer loop index) when computing the weighted sum. Resolved by computing the category average directly from actualPoints / totalPoints rather than reading back from the list.
• Incorrect weighted average: Initially the program summed grades without dividing by total weight, causing incorrect results when weights didn't add up to 100. Fixed by dividing weightedSum by totalWeight.

Demo Video

Screen.Recording.2026-04-26.at.9.23.37.PM.1.mp4

How to Run

# Compile
g++ -o grade_calculator main.cpp
# Run
./grade_calculator
Then follow the on-screen prompts to enter your course's grading structure and scores.

Future Improvements

• Add "guardrails" to prevent unrealistic grade calculations
• Add a potential grade calculator mode (already scaffolded in main())
• Support letter grade output (A/B/C/D/F) alongside percentage
• Allow users to save and load grade data from a file
• Build a simple GUI using a library like Qt or Dear ImGui

Project by AJ Arguello | Fall/2025