How to Evaluate Custom Math Expressions in C without Python Integration

Evaluating complex mathematical expressions in C can prove challenging without external libraries or runtime environments. However, the ExprTk library provides an elegant and efficient solution.

Let's consider an example expression:

3   sqrt(5)   pow(3, 2)   log(5)

Using ExprTk, we can tackle this problem in a straightforward manner:

#include 
#include 
#include "exprtk.hpp"

int main() {
  // Define types for expression and parser
  typedef exprtk::expression expression_t;
  typedef exprtk::parser parser_t;

  // Store the expression as a string
  std::string expression_string = "3   sqrt(5)   pow(3,2)   log(5)";

  // Instantiate expression and parser objects
  expression_t expression;
  parser_t parser;

  // Compile the expression string
  if (parser.compile(expression_string, expression)) {
    // Evaluate the expression
    double result = expression.value();

    // Print the result
    printf("Result: .15f\n", result);
  } else {
    // Handle compilation errors
    printf("Error in expression\n.");
  }

  return 0;
}

This code:

1. Includes the necessary headers and loads ExprTk.
2. Defines an expression and parser, ensuring type safety for double-precision values.
3. Stores the custom expression as a string.
4. Compiles the expression string into an expression object.
5. Evaluates the expression and prints the result.

By leveraging the ExprTk library, you can efficiently handle the evaluation of complex math expressions in C , alleviating the need for Python integration.