Идентификатор “error” не определен

#include "stdafx.h"
#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>
using namespace std;
inline void keep_window_open() {
char ch; 
cin >> ch;
}
class Token {
public:
char kind;
double value;
};
Token get_token();
vector<Token>tok;
int main(int argc, char* argv[])
{
while (cin) {
    Token t = get_token();
    tok.push_back(t);
}
for (int i = 0; i < tok.size(); ++i) {
    if (tok[i].kind == '*') {
        double d = tok[i - 1].value*tok[i + 1].value;
    }
}
cout << "Enter(+, -, *, /):\n";
cout << "Enter x at the end (8-2*2x):";
int lval = 0;
int rval;
cin >> lval;
if (!cin)
{ 
    error ("neverno");
}
for (char op; cin >> op;)
{
    if (op != 'x')
    {
        cin >> rval;
    }
    if (!cin)
    {
        error("neverno");
    }
    switch (op)
    {
    case '+':
        lval += rval;
        break;
    case '-':
        lval -= rval;
        break;
    case '*':
        lval *= rval;
        break;
    case '/':
        lval /= rval;
        break;
    default:
        cout << "result:" << lval << '\n';
        keep_window_open();
        return 0;
    }
}
error("neverno");
}