/*

**************************************************************

* C++ Mathematical Expression Toolkit Library *

* *

* Simple Example 18 *

* Author: Arash Partow (1999-2025) *

* URL: https://www.partow.net/programming/exprtk/index.html *

* *

* Copyright notice: *

* Free use of the Mathematical Expression Toolkit Library is *

* permitted under the guidelines and in accordance with the *

* most current version of the MIT License. *

* https://www.opensource.org/licenses/MIT *

* SPDX-License-Identifier: MIT *

* *

**************************************************************

*/

#include <cstdio>

#include <string>

#include "exprtk.hpp"

template <typename T>

void file_io()

{

typedef exprtk::symbol_table<T> symbol_table_t;

typedef exprtk::expression<T> expression_t;

typedef exprtk::parser<T> parser_t;

const std::string fileio_program =

" var file_name := 'file.txt'; "

" var stream := null; "

" "

" if (stream := open(file_name,'w')) "

" println('Successfully opened file: ' + file_name); "

" else "

" { "

" println('Failed to open file: ' + file_name); "

" return [false]; "

" }; "

" "

" var s := 'Hello world...\n'; "

" "

" for (var i := 0; i < 10; i += 1) "

" { "

" write(stream,s); "

" }; "

" "

" if (close(stream)) "

" println('Sucessfully closed file: ' + file_name); "

" else "

" { "

" println('Failed to close file: ' + file_name); "

" return [false]; "

" } ";

exprtk::rtl::io::file::package<T> fileio_package;

exprtk::rtl::io::println<T> println;

symbol_table_t symbol_table;

symbol_table.add_function("println",println);

symbol_table.add_package (fileio_package );

expression_t expression;

expression.register_symbol_table(symbol_table);

parser_t parser;

parser.compile(fileio_program,expression);

printf("Result %10.3f\n",expression.value());

}

int main()

{

file_io<double>();

return 0;

}