Help with passing in a boolean for a function.

[jollyholly11]

For my code I am trying to pass in a boolean isPowerTwo into the function void Shuffle, to check if the vector string restaurant is a power of two. However when I run my code it states:
terminate called after throwing an instance of 'std::out_of_range'
what(): vector::_M_range_check: __n (which is 1) >= this->size() (which is 1)

#include <iostream>
#include <cmath>
#include <string>
#include <cstdlib>
#include <iomanip>
#include <ctime>
#include <math.h>
#include <stdio.h>
#include <vector>
#include <stdlib.h>
#include <string>
#include <fstream>
#include <limits>

using namespace std;

const int NOT_FOUND = -1;

//Initialize Vector
vector<string> initialize() {
	vector<string> restaurants;
	return restaurants;

}

//Showing all the restaurants
void printRestaurants(vector<string>& restaurants) {
	cout << "Here are the current restaurants: " << endl << endl;
	for (int index = 0; index < restaurants.size(); index++) {
		if (index < restaurants.size() - 1) {
			cout << "\t" << "\"" << restaurants[index] << "\" " << endl;
		}
		else
			cout << "\t" << "\"" << restaurants[index] << "\"" << endl;
	}

}

//Finding the restaurant name from the user
int find(string restaurantName, vector<string> restaurants) {
	for (int index = 0; index < restaurants.size(); index++) {
		if (restaurantName == restaurants[index]) {
			return index;
		}
	}
	return NOT_FOUND;
}

//Add a restaurant
void addRestaurant(string restaurantName, vector<string>& restaurants) {
	int found = find(restaurantName, restaurants);
	if (found == NOT_FOUND) {
		restaurants.push_back(restaurantName);
		cout << restaurantName << " has been added." << endl;
	}
	else {
		cout << "That restaurant is already on the list, you can not add it again." << endl;
	}
}

//Remove a restaurant
void removeRestaurant(string restaurantName, vector<string>& restaurants) {
	int found = find(restaurantName, restaurants);
	if (found != NOT_FOUND) {
		int last_pos = restaurants.size() - 1;
		restaurants.erase(restaurants.begin() + found);
		cout << restaurantName << " has been removed." << endl;
	}
	else {
		cout << "That restaurant is not on the list, you can not remove it." << endl;
	}
}

void removeLoserRestaurant(string restaurantName, vector<string>& restaurants) {
	int found = find(restaurantName, restaurants);
	if (found != NOT_FOUND) {
		int last_pos = restaurants.size() - 1;
		restaurants.erase(restaurants.begin() + found);
	}
	else {
		cout << "The restaurant" << restaurantName << "was not removed because it was not in the vector" << endl;
	}
}

////Cut the list of restaurants
void cutRestaurant(vector<string>& restaurants) {
	vector<string> changeVector = restaurants;
	//int blastedChoice = cutChoice;
	const int OUT_OF_RANGE = 0;
	int cutChoice = 0;
	cin >> cutChoice;
	
	while (cutChoice > changeVector.size() || cutChoice < OUT_OF_RANGE || cin.fail()) {
		cin.clear();
		cin.ignore(numeric_limits<streamsize>::max(), '\n');
		cout << endl << "The cut number must be between 0 and " << changeVector.size() << endl;
		cout << "How many restaurants should be taken from the top and put on the bottom?" << endl;
		cin >> cutChoice;
	}
	for (int i = 0; i < cutChoice; i++) {
		changeVector.at(i) = restaurants.at(0);
		restaurants.erase(restaurants.begin());
	}
	for (int j = 0; j < cutChoice; j++) {
		restaurants.push_back(changeVector.at(j));
	}
	return; 
}
	
//bool isPowerTwo(int x) {
//	return !(x & (x - 1));
//}

bool isPowerTwo(int x) { //x = restaurants.size()
	int blastedTwo = 2;
	while (x > 1) {
		if (x % 2 != 0) {
			return false;
		}
		x /= 2;
	}
	return true;
}

//Shuffling the Vector Restaurants
void shuffleVector(vector<string>& restaurants) {

	vector<string> newVector;
	vector<string> firstVector;
	if (isPowerTwo(restaurants.size())) {
	for (int i = 0; i < ((restaurants.size() / 2) - 1); i++) {
		firstVector.push_back(restaurants.at(i));
	}
	for (int i = ((restaurants.size() / 2) - 1); i < restaurants.size(); i++) {
		lastVector.push_back(restaurants.at(i));
	}

	for (int i = 0; i < restaurants.size() / 2; i++) {
		newVector.push_back(firstVector.at(i));
		newVector.push_back(lastVector.at(i));
	}
	restaurants = newVector;
}
else {
		cout << "The current tournament size(" << restaurants.size() << ") is not a power of two(2, 4, 8...)." << endl;
		cout << "A shuffle is not possible. Please add or remove restaurants." << endl;
	}
}

// Main Function
int main() {
	srand(time(0));
	vector<string> restaurants;
	int menu = 1;
	bool done = false;
	int menuOption = 1;
	int cutChoice = 1;
	const int BLASTED_ONE_THOUSAND = 1000;
	const string QUIT_OPTION = "quit";
	const string DISPLAY_RESTAURANTS = "display";
	const string ADD_RESTAURANT = "add";
	const string REMOVE_RESTAURANT = "remove";
	const string CUT_VECTOR = "cut";
	const string SHUFFLE_VECTOR = "shuffle";
	string userInput;

	//vector<string> restaurants = initialize();
	cout << "Welcome to the restaurant battle! Enter \"options\" to see options." << endl << endl;
	/*cout << "Enter your selection:" << endl;
	cin >> userInput;*/

	while (!done) {
		cout << "Enter your selection:" << endl;
		cin >> userInput;
		cin.ignore(); // i am just trying to get this to work!!!!!!!
	
		if (userInput == DISPLAY_RESTAURANTS) {
			printRestaurants(restaurants);
			cout << endl;
		}
		else if (userInput == ADD_RESTAURANT) {
			cout << "What is the name of the restaurant you want to add?" << endl;
			string restaurantName;
			getline(cin, restaurantName);
			//cout << "Will this pause 1" << endl;
			addRestaurant(restaurantName, restaurants);
			cout << endl;
		}
		else if (userInput == REMOVE_RESTAURANT) {
			cout << "What is the name of the restaurant you want to remove ? " << endl;
			string restaurantName;
			getline(cin, restaurantName);
			removeRestaurant(restaurantName, restaurants);
			cout << endl;
		}
		else if (userInput == CUT_VECTOR) {
			cout << "How many restaurants should be taken from the top and put on the bottom?" << endl;
			//string cutChoice;
			//getline(cin, cutChoice);
			
			cutRestaurant(restaurants);
			cout << endl;
		}
		else if (userInput == SHUFFLE_VECTOR) {
			//cout << "Did this actually enter this vector" << endl;
			shuffleVector(restaurants);
			cout << endl;
		}

		}
		else if (userInput == QUIT_OPTION) {
			menu = 0;
			cout << endl;
			cout << "Goodbye!" << endl;
			//done = true;
			return 0;
		}
		else {
			cin.clear();
			cin.ignore(BLASTED_ONE_THOUSAND, '\n');
			cout << "Invalid selection " << endl;
			printMenu();
		}
	}


//system("pause");
	return 0;
}

[JLBorges]

#include <iostream>
#include <limits>
#include <vector>
#include <string>
#include <algorithm>
#include <random>
#include <iomanip>

std::size_t get_cut_number( std::size_t sz ) {

    std::cout << "How many restaurants should be taken from the top and put at the bottom?\n"
              << "The cut number must be between 0 and " << sz-1 << ": " ;

    std::size_t cut_number ;
    if( std::cin >> cut_number ) {

        if( cut_number < sz ) return cut_number ;
        else std::cout << "the value is out of range. try again.\n" ;
    }

    else
    {
        std::cout << "error: non-integer input. try again\n" ;
        std::cin.clear() ;
        std::cin.ignore( std::numeric_limits<std::streamsize>::max(), '\n' );
    }

    return get_cut_number(sz) ;
}

std::vector<std::string>& cutRestaurant( std::vector<std::string>& restaurants, std::size_t cut_number ) {

    // http://en.cppreference.com/w/cpp/algorithm/rotate
    std::rotate( restaurants.begin(), restaurants.begin()+cut_number, restaurants.end() ) ;
    return restaurants ;
}

std::vector<std::string>& shuffleVector( std::vector<std::string>& restaurants ) {
    
    // http://en.cppreference.com/w/cpp/numeric/random
    static std::mt19937 engine( std::random_device{}() ) ;
    
    // http://en.cppreference.com/w/cpp/algorithm/random_shuffle
    std::shuffle( restaurants.begin(), restaurants.end(), engine ) ;
    return restaurants ;
}

void printRestaurants( const std::vector<std::string>& restaurants) {

    std::cout << "Here are the current restaurants:\n" ;
    
    // http://www.stroustrup.com/C++11FAQ.html#for
    // http://www.stroustrup.com/C++11FAQ.html#auto
    // http://en.cppreference.com/w/cpp/io/manip/quoted
    for( const auto& r : restaurants ) std::cout << std::quoted(r) << "  " ;
    std::cout << '\n' ;
}

int main()
{
    std::vector<std::string> restaurants { "abc", "def g", "ij klmn", "opq", "rs", "tuv", "wxyz" } ;
    printRestaurants(restaurants) ;

    const std::size_t cut_number = get_cut_number( restaurants.size() ) ;
    cutRestaurant( restaurants, cut_number ) ;
    std::cout << "\nafter cutRestaurant (cut_number==" << cut_number << "): " ;
    printRestaurants(restaurants) ;

    shuffleVector(restaurants) ;
    std::cout << "\nafter shuffleVector: " ;
    printRestaurants(restaurants) ;
}

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