#include "exprtk.hpp"

typedef exprtk::symbol_table<double> symbol_table_t;
typedef exprtk::expression<double>   expression_t;
typedef exprtk::parser<double>       parser_t;

double x, y;

symbol_table_t symbol_table;
symbol_table.add_variable("x", x);
symbol_table.add_variable("y", y);
symbol_table.add_constants();

expression_t expression;
expression.register_symbol_table(symbol_table);

std::string expression_str = "x^2 + y^2";
parser_t parser;
parser.compile(expression_str, expression);