#include

#include

#include

#include

using namespace std;

$/**$

Tests if a token is an operator.

@param token the token

@return true if the token is one of: $+-*/^$

$*/$

bool is$\_$operator$($string token$)$

$\{$

return token $=="+"||$ token $=="-"||$ token $=="*"||$ token $=="/"$;

$\}$

$/**$

Tests if a token is a digit.

@param token the token

@return true if token is one of: $0123456789$

$*/$