Need help with getting a random function to connect with an array of structs

anbrick · #1 09-Dec-2008, 18:49

A little background information...

I'm in my first programming class, and we are required to create a "game" in C++ as a final project. My game consists of asking for the capital of a given country. When the question is asked, the player will be given 3 capitals to pick from. If the player guesses correctly, they get a point and the game continues. If the player guesses incorrectly, they get a strike. When the player accumulates 3 strikes, the game is over.

Having said all of that, I've written a random function that will randomly select one of the countries I have. There are 130 countries to pick from. My problem is that I don't know how to associate the random function with my countries.

With the way my game is set up, my professor said I needed to make my countries and capital choices into an array of structs.

CPP / C++ / C Code:


#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include <stdlib.h>
#include <sys/time.h>
using namespace std;

struct Question {
  string country;
  string capital1;
  string capital2;
  string capital3;
  short correctAnswer;
};

Question QL[150]= {
                    {"Afghanistan", "Brussels", "Moroni", "Kabul", 3},
                    {"Albania", "Tirane", "Gaborone", "Brasilia", 1},
                    {"Algeria", "Algiers", "Jakarta", "Zagreb", 3},
                    {"Angola", "San Salvador", "Luanda", "Malabo", 2},
                    {"Argentina", "Buenos Aires", "Managua", "Lilongwe", 1}
};

int QLSize = sizeof(QL);

void displayQuestion(Question QL) {
   cout << "What is the captital of " << QL.country << "? " << endl;
   cout << endl;
   cout << endl;
   cout << "1. " << QL.capital1 << endl;
   cout << endl;
   cout << "2. " << QL.capital2 << endl;
   cout << endl;
   cout << "3. " << QL.capital3 << endl;
}

void setuprand() {
  struct timeval tv; struct timezone tz;
  gettimeofday(&tv, &tz);
  srand(tv.tv_usec);
}

double random(double m, double n) {
 double  ans = m + ((n - m + 1) * (rand() / (RAND_MAX + 1.0)));
 return static_cast<int>(ans); 
}

int main() {

 return 0;
}

Please.. Someone help me. This is due Wednesday night, and I still have so much left to do.

WaltP · #2 09-Dec-2008, 21:51

You want a random number from 0 to 129. That number is used as an index into your struct array:

Code:

num = rand()...
QL[num] is the structure of the random country.

Keep in mind that once you use a particular random number (say 20), you don't want to use it again. You should have some way to test if rand() gives you a number again.

Mexican Bob · #3 15-Dec-2008, 05:36

Quote:

Originally Posted by anbrick

Please.. Someone help me. This is due Wednesday night, and I still have so much left to do.

I think that your instructor is probably looking for something like this:

CPP / C++ / C Code:

#include <iostream>

typedef struct st_capitals
{
    char* country;
    char* capital;
} CAPITALS;

const CAPITALS capitals[] = 
{{"Afghanistan", "Kabul"},
{"Albania", "Tirane"},
{"Algeria", "Algiers"},
{"Andorra", "Andorra la Vella"},
{"Angola", "Luanda"},
{"Antigua and Barbuda", "Saint John's"},
{"Argentina", "Buenos Aires"},
{"Armenia", "Yerevan"},
{"Australia", "Canberra"},
{"Austria", "Vienna"},
{"Azerbaijan", "Baku"},
{"The Bahamas", "Nassau"},
{"Bahrain", "Manama"},
{"Bangladesh", "Dhaka"},
{"Barbados", "Bridgetown"},
{"Belarus", "Minsk"},
{"Belgium", "Brussels"},
{"Belize", "Belmopan"},
{"Benin", "Porto-Novo"},
{"Bhutan", "Thimphu"},
{"Bolivia", "La Paz"},
{"Bosnia and Herzegovina", "Sarajevo"},
{"Botswana", "Gaborone"},
{"Brazil", "Brasilia"},
{"Brunei", "Bandar Seri Begawan"},
{"Bulgaria", "Sofia"},
{"Burkina", "Faso - Ouagadougou"},
{"Burundi", "Bujumbura"},
{"Cambodia", "Phnom Penh"},
{"Cameroon", "Yaounde"},
{"Canada", "Ottawa"},
{"Cape Verde", "Praia"},
{"Central African Republic", "Bangui"},
{"Chad", "N'Djamena"},
{"Chile", "Santiago"},
{"China", "Beijing"},
{"Colombia", "Bogota"},
{"Comoros", "Moroni"},
{"Congo - Republic of the", "Brazzaville"},
{"Congo - Democratic Republic of the", "Kinshasa"},
{"Costa Rica", "San Jose"},
{"Cote d'Ivoire", "Yamoussoukro"},
{"Croatia", "Zagreb"},
{"Cuba", "Havana"},
{"Cyprus", "Nicosia"},
{"Czech Republic", "Prague"},
{"Denmark", "Copenhagen"},
{"Djibouti", "Djibouti"},
{"Dominica", "Roseau"},
{"Dominican Republic", "Santo Domingo"},
{"East Timor (Timor-Leste)", "Dili"},
{"Ecuador", "Quito"},
{"Egypt", "Cairo"},
{"El Salvador", "San Salvador"},
{"Equatorial Guinea", "Malabo"},
{"Eritrea", "Asmara"},
{"Estonia", "Tallinn"},
{"Ethiopia", "Addis Ababa"},
{"Fiji", "Suva"},
{"Finland", "Helsinki"},
{"France", "Paris"},
{"Gabon", "Libreville"},
{"The Gambia", "Banjul"},
{"Georgia", "Tbilisi"},
{"Germany", "Berlin"},
{"Ghana", "Accra"},
{"Greece", "Athens"},
{"Grenada", "Saint George's"},
{"Guatemala", "Guatemala City"},
{"Guinea", "Conakry"},
{"Guinea-Bissau", "Bissau"},
{"Guyana", "Georgetown"},
{"Haiti", "Port-au-Prince"},
{"Honduras", "Tegucigalpa"},
{"Hungary", "Budapest"},
{"Iceland", "Reykjavik"},
{"India", "New Delhi"},
{"Indonesia", "Jakarta"},
{"Iran", "Tehran"},
{"Iraq", "Baghdad"},
{"Ireland", "Dublin"},
{"Israel", "Jerusalem"},
{"Italy", "Rome"},
{"Jamaica", "Kingston"},
{"Japan", "Tokyo"},
{"Jordan", "Amman"},
{"Kazakhstan", "Astana"},
{"Kenya", "Nairobi"},
{"Kiribati", "Tarawa Atoll"},
{"Korea, North", "Pyongyang"},
{"Korea, South", "Seoul"},
{"Kosovo", "Pristina"},
{"Kuwait", "Kuwait City"},
{"Kyrgyzstan", "Bishkek"},
{"Laos", "Vientiane"},
{"Latvia", "Riga"},
{"Lebanon", "Beirut"},
{"Lesotho", "Maseru"},
{"Liberia", "Monrovia"},
{"Libya", "Tripoli"},
{"Liechtenstein", "Vaduz"},
{"Lithuania", "Vilnius"},
{"Luxembourg", "Luxembourg"},
{"Macedonia", "Skopje"},
{"Madagascar", "Antananarivo"},
{"Malawi", "Lilongwe"},
{"Malaysia", "Kuala Lumpur"},
{"Maldives", "Male"},
{"Mali", "Bamako"},
{"Malta", "Valletta"},
{"Marshall Islands", "Majuro"},
{"Mauritania", "Nouakchott"},
{"Mauritius", "Port Louis"},
{"Mexico", "Mexico City"},
{"Micronesia - Federated States of", "Palikir"},
{"Moldova", "Chisinau"},
{"Monaco", "Monaco"},
{"Mongolia", "Ulaanbaatar"},
{"Montenegro", "Podgorica"},
{"Morocco", "Rabat"},
{"Mozambique", "Maputo"},
{"Myanmar (Burma)", "Rangoon (Yangon)"},
{"Namibia", "Windhoek"},
{"Nauru", "no official capital; government offices in Yaren District"},
{"Nepal", "Kathmandu"},
{"Netherlands", "Amsterdam"},
{"New Zealand", "Wellington"},
{"Nicaragua", "Managua"},
{"Niger", "Niamey"},
{"Nigeria", "Abuja"},
{"Norway", "Oslo"},
{"Oman", "Muscat"},
{"Pakistan", "Islamabad"},
{"Palau", "Melekeok"},
{"Panama", "Panama City"},
{"Papua New Guinea", "Port Moresby"},
{"Paraguay", "Asuncion"},
{"Peru", "Lima"},
{"Philippines", "Manila"},
{"Poland", "Warsaw"},
{"Portugal", "Lisbon"},
{"Qatar", "Doha"},
{"Romania", "Bucharest"},
{"Russia", "Moscow"},
{"Rwanda", "Kigali"},
{"Saint Kitts and Nevis", "Basseterre"},
{"Saint Lucia", "Castries"},
{"Saint Vincent and the Grenadines", "Kingstown"},
{"Samoa", "Apia"},
{"San Marino", "San Marino"},
{"Sao Tome and Principe", "Sao Tome"},
{"Saudi Arabia", "Riyadh"},
{"Senegal", "Dakar"},
{"Serbia", "Belgrade"},
{"Seychelles", "Victoria"},
{"Sierra Leone", "Freetown"},
{"Singapore", "Singapore"},
{"Slovakia", "Bratislava"},
{"Slovenia", "Ljubljana"},
{"Solomon Islands", "Honiara"},
{"Somalia", "Mogadishu"},
{"South Africa", "Pretoria"},
{"Spain", "Madrid"},
{"Sri Lanka", "Colombo"},
{"Sudan", "Khartoum"},
{"Suriname", "Paramaribo"},
{"Swaziland", "Mbabane"},
{"Sweden", "Stockholm"},
{"Switzerland", "Bern"},
{"Syria", "Damascus"},
{"Taiwan", "Taipei"},
{"Tajikistan", "Dushanbe"},
{"Tanzania", "Dar es Salaam"},
{"Thailand", "Bangkok"},
{"Togo", "Lome"},
{"Tonga", "Nuku'alofa"},
{"Trinidad and Tobago", "Port-of-Spain"},
{"Tunisia", "Tunis"},
{"Turkey", "Ankara"},
{"Turkmenistan", "Ashgabat"},
{"Tuvalu", "Vaiaku village, Funafuti province"},
{"Uganda", "Kampala"},
{"Ukraine", "Kyiv"},
{"United Arab Emirates", "Abu Dhabi"},
{"United Kingdom", "London"},
{"United States of America", "Washington D.C."},
{"Uruguay", "Montevideo"},
{"Uzbekistan", "Tashkent"},
{"Vanuatu", "Port-Vila"},
{"Vatican City", "Vatican City"},
{"Venezuela", "Caracas"},
{"Vietnam", "Hanoi"},
{"Yemen", "Sanaa"},
{"Zambia", "Lusaka"},
{"Zimbabwe", "Harare"}};

int main()
{
    for( size_t i = 0; i < sizeof(capitals)/sizeof(CAPITALS); i++ )
    {
        std::cout << "Country: " << capitals[i].country << "\nCapital: " << capitals[i].capital << "\n" << std::endl;
    }
    return 0;
}

...as the array of structs. I wouldn't embed the "wrong answers" into the structure. You are creating a lot of extra work for yourself. If you want to have a right choice and some number of wrong choices, you only have to pick 3 or 4 random elements out of the structure and then use the "wrong" capitals (indexes into the structure) as your data to display to the user. No sense in storing a bunch of extra data. You already have it!

Let me know if you want a hint as to how to accomplish what I'm suggesting.

Bob de Mexican

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Need help with getting a random function to connect with an array of structs

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