How can I efficiently evaluate custom mathematical expressions in C ?

Evaluating Mathematical Expressions in C

Evaluating custom mathematical expressions in C can be a challenging task. Embedding Python into C is one potential solution, but there are more efficient and native options available.

Utilizing the ExprTk Library

One of the most effective approaches is the ExprTk library. This library provides a convenient and powerful expression parser and evaluator. Here's a simple example using ExprTk:

<code class="cpp">#include <cstdio>
#include <string>
#include "exprtk.hpp"

int main() {
  // Define expression types
  typedef exprtk::expression<double> expression_t;
  typedef exprtk::parser<double> parser_t;

  // Expression string
  std::string expression_string = "3 + sqrt(5) + pow(3,2) + log(5)";

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

  // Compile expression
  if (parser.compile(expression_string, expression)) {
    // Evaluate and print result
    double result = expression.value();
    printf("Result: %19.15\n", result);
  } else {
    printf("Error in expression\n.");
  }

  return 0;
}</code>

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