c-eval.cc

/*
 *	C Expression Evaluator - C example
 *
 *	This program is distributed under the terms of the GPL v3.0 or later
 *	Download the GNU Public License (GPL) from <https://www.gnu.org>
 *
 *	Copyright(C) 2025, Free Software Foundation, Inc.
 *	Written by Nicholas Christopoulos <mailto:netnic@proton.me>
 */

#include <cstdio>
#include <cstring>
#include <climits>
#include "cexp.cc"

int main(int argc, char *argv[]) {
	char	expr[LINE_MAX] = {};
	CExp	cexp;	// the engine
	CVar	result;	// a variable to put the result

	// create the expression from arguments
	for ( int i = 1; i < argc; i ++ )
		if ( strcmp(argv[i], "-d") == 0 ) cexp.verbose = 1;
		else strcat(expr, argv[i]);

	// if no CLI arguments; read the expression from stdin
	if ( strlen(expr) == 0 ) {
		while ( fgets(expr, LINE_MAX, stdin) ) {
			char *p = expr;
			while ( isspace(*p) ) p ++;
			if ( strlen(expr) ) { // not empty string
				if ( (strcmp(p, "q") == 0) || (strcmp(p, "quit") == 0)	// exit command
					|| (strcmp(p, "x") == 0) || (strcmp(p, "exit") == 0) )
					return 0;
				// execute the expression
				result.clear();
				if ( cexp.evaluate(expr, &result) != E_SUCCESS )
					printf("error: (%d) %s\n", cexp.error_code, cexp.error_message.c_str());
				else
					result.print();
				}
			}
		}
	else {
		// execute from arguments
		if ( cexp.evaluate(expr, &result) != E_SUCCESS )
			printf("error: (%d) %s\n", cexp.error_code, cexp.error_message.c_str());
		else
			result.print();
		}

	return 0;
	}