https://github.com/abdnh/math-eval
Math expression evaluator
https://github.com/abdnh/math-eval
algorithm math math-evaluator math-expression-evaluator mathematics
Last synced: 3 months ago
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Math expression evaluator
- Host: GitHub
- URL: https://github.com/abdnh/math-eval
- Owner: abdnh
- License: mit
- Created: 2021-08-02T23:23:19.000Z (almost 4 years ago)
- Default Branch: master
- Last Pushed: 2021-08-22T23:28:10.000Z (almost 4 years ago)
- Last Synced: 2025-01-24T07:29:49.224Z (4 months ago)
- Topics: algorithm, math, math-evaluator, math-expression-evaluator, mathematics
- Language: C
- Homepage:
- Size: 28.3 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Math Expression Evaluator
This is just a math expression evaluator in C that I wrote for fun and learning.
If you want a production-quality library, take a look at [TinyExpr](https://github.com/codeplea/tinyexpr).
## Description
The [Shunting-yard algorithm](https://en.wikipedia.org/wiki/Shunting-yard_algorithm) is used for parsing
expressions written in [Infix notation](https://en.wikipedia.org/wiki/Infix_notation) (e.g. `5 + 3`).
My implementation parses operators and operands and store each type in a separate stack (`ops_stack` and `operands_stack`)
for ease of computation, and doesn't provide a function to
produce an expression in [Reverse Polish notation](https://en.wikipedia.org/wiki/Reverse_Polish_notation) yet.
## How to use
To use as a library, copy the necessary sources (all but demo.c, debug.*, tests.c) to your project
and include `evaluate.h`.
See [evaluate.h](evaluate.h) for some docs and [demo.c](demo.c) for a usage example.
## Repo structure
- [demo.c](demo.c) a simple calculator built using the library.
- [evaluate.c](evaluate.c) uses the [Shunting-yard algorithm](https://en.wikipedia.org/wiki/Shunting-yard_algorithm)
to evaluate expressions written in [infix notation](https://en.wikipedia.org/wiki/Infix_notation).
- [ops.c](ops.c) defines the supported operations.
- [stack.h](stack.h) is a stack implementation to support the algorithm. It's based on the [vector.h](vector.h) file, which
I originally wrote for use in my C utilities, so it's generic (i.e macro hell).
- [debug.c](debug.c) prints some debugging info when the `EVAL_DEBUG` macro is defined.
- [tests.c](tests.c): some tests
## Building
To build and run the demo, run:
```
make demo
```
To run tests:
```
make tests
```
## TODO
- More operations and constants
- Explore more algorithms for mathematical expression parsing
- Rust version
- Use an arbitrary-precision arithmetic library to save myself from headaches
- [Operator associativity](https://en.wikipedia.org/wiki/Operator_associativity). Currently, the exponentiation operator (^) is special-cased to be right-associative.
If I'll ever add more right-associative operators, I should modify the `operator` struct to store associativity and remove the special case.