A command-line program that tokenizes an infix arithmetic expression, converts it to postfix notation using the Shunting Yard Algorithm, and evaluates the result using a custom stack implementation.
Also includes a gamified web interface (index.html) built with the same logic.
g++ tokenizer.cpp converter.cpp evaluator.cpp main.cpp -o program./programType your expression and press Enter.
Input:
a + b * (c + 2)
Output:
a b c 2 + * +
Enter value for a: 3
Enter value for b: 5
Enter value for c: 2
23
- Full tokenizer with C++ identifier validation
- Infix to postfix using Shunting Yard Algorithm
- Supports all 3 bracket types —
()[]{} - Unary minus support —
-a,-(a+b) - Custom stack using linked list (no STL stack)
- Variable prompts via
stderr, result viastdout - Proper exit codes for all error types
| Code | Meaning | Example |
|---|---|---|
| 0 | Success | a + b * c |
| 1 | Syntax error | a ++ b, (a + b] |
| 2 | Runtime error | division by zero |
| 3 | Logical error | empty expression, () |
| Input | Expected |
|---|---|
a + b * (c + 2) |
a b c 2 + * + → 23 |
{a + [b * (c + d)]} |
a b c d + * + → 15 |
-a + b |
0 a - b + |
(a + b] |
Syntax error: mismatched brackets |
a / b (b=0) |
Runtime error: division by zero |
() |
Logical error: empty brackets |
*a + b |
Syntax error: cannot start with * |
infix-engine/
├── main.cpp → entry point, handles I/O and exit codes
├── tokenizer.h/cpp → breaks expression into typed tokens
├── converter.h/cpp → infix to postfix (Shunting Yard Algorithm)
├── evaluator.h/cpp → evaluates postfix using a stack
├── stack.h → custom linked list stack implementation
├── index.html → gamified web interface
└── screenshots/
├── window.png
└── terminal.png
Open index.html in any browser for an interactive gamified version with XP, coins and streak system.
Live demo: ** https://kamer-heap.github.io/infix-engine/**
Built with C++ | Custom Stack | Shunting Yard Algorithm