Mathematical Expressions for C

• Mathematical Expressions for C
  • What is Mathex?
  • How to use? (C)
  • How to use? (C++)
  • Building from source

What is Mathex?

Mathematical Expressions (or Mathex for short) is a library for C/C++ that evaluates mathematical expressions from strings at runtime according to Mathex Specification. It aims to provide fast, easy, customizable and, most importantly, safe evaluation with no dependencies.

The library is completely C99 standard compliant.

How to use? (C)

Using Mathex is super easy - just include one header, initialize, evaluate and free. That's it.

#include <mathex.h>
#include <stdio.h>

int main() {
    // Use `mx_create` and `MX_DEFAULT` to get default settings.
    // For what settings are available, check out documentation.
    mx_config *config = mx_create(MX_DEFAULT);

    // Config that you get from `mx_create` contains your settings
    // along with custom variables and functions you inserted.
    double x = 1.5;
    mx_add_variable(config, "x", &x);

    // These variables and functions are then available for users
    // to use in expressions.
    char *input = "2x + 5";
    double result;

    // Mathex writes result of evaluation into the address you provide.
    // Here we pass an address to a `result` variable we declared above.
    if (mx_evaluate(config, input, &result) == MX_SUCCESS) {
        // Outputs `2x + 5 is 8`
        printf("%s is %.0lf\n", input, result);
    }

    // Don't forget to free the memory once you are done.
    mx_free(config);
}

Don't forget to link Mathex when you compile your program:

cc program.c -lmathex -lm

How to use? (C++)

Mathex also provides C++ friendly interface using separate header. It allows to use C++ strings and lambda expressions.

#include <iostream>
#include <mathex.hpp>
#include <string>

int main() {
    // Use `Config` class and `DefaultFlags` to get default settings.
    // For what settings are available, check out documentation.
    mathex::Config config(mathex::DefaultFlags);

    // Config class wraps `mx_config` that contains your settings
    // along with custom variables and functions you inserted.
    double x = 1.5;
    config.addVariable("x", x);

    // These variables and functions are then available for users
    // to use in expressions.
    std::string input = "2x + 5";
    double result;

    // Mathex writes result of evaluation into the reference you provide.
    // Here we pass a reference to a `result` variable we declared above.
    if (config.evaluate(input, result) == mathex::Success) {
        // Outputs `2x + 5 is 8`
        std::cout << input << " is " << result << std::endl;
    }

    // No need to manually free - the memory is automatically
    // freed once `config` object goes out of scope.
}

Don't forget to link Mathex when you compile your program:

c++ program.cpp -lmathex

Building from source

To build the library, you need to clone the repository using Git and build the binary using GNU Make:

git clone https://github.com/capsey/mathex-c.git
cd ./mathex-c
make # to specify compiler: CC=clang make

It will use default C compiler on your system (cc). If you want to use specific compiler, export environment variable CC with your desired compiler before running make.

After compilation, library binary will be in bin directory. The header files are located in include directory.