Why is my vector initialisation making all objects in my array the same? - c++

Question

I'm working on a program to aid me in world-building that randomly generates a settlement (hamlet, village, town, city) based on a nation (German, Latin, Eastern) that the user chooses. I've integrated a sort of settler generation system to create settlers within the settlement, each with a name, age, gender, and wealth using a constructor and holding the results as objects within a vector. Unfortunately, the program creates an entire population of clones, filling the vector with settlers with the same name, age, etc.
I've tried initialising the Settler class' constructor in a for loop, but that hasn't changed anything except causing you to get a different set of settlers each time you request information on one of them.
Settler Constructor:
class Settler {
public:
int settlerAge;
string settlerName;
string settlerGender;
string settlerWealth;
Settler(int type, int nation, int quantity) {
int result{};
string givenName{};
string surName{};
// Latin Male First Name
string latinMaleName[15] = {"Faustus", "Mamercus", "Mettius", "Appius", "Hostus", "Quintus", "Cossus", "Secundus", "Servius", "Gallio", "Tettienus", "Petronius", "Paesentius", "Pescunnius", "Clodius"};
// Latin Surname
string latinSurname[30] = {"Natalinus", "Lucilianus", "Crispian", "Laetinianus", "Falco", "Otho", "Plautius", "Pascentius", "Lepidus", "Moderatus", "Caeparius", "Caetronius", "Hostilius", "Aedinius", "Papius", "Gennadia", "Triaria", "Planta","Amantia", "Mico", "Opilio", "Augusta", "Laevina", "Longina", "Mico", "Servana", "Sicula", "Iovina", "Albana", "Concessa"};
// Latin Female First Name
string latinFemaleName[15] = {"Vorenia", "Tuccia", "Consentia", "Vinicia", "Aurelia", "Helvia", "Fabia", "Aemilia", "Petilia", "Cloelia", "Viducia", "Betiliena", "Sornatia", "Memmia", "Pedia"};
// As above, so below...
string germanMaleName[15] = {"Carsten", "Benedikt", "Emmerich", "Tillmann", "Maik", "Severin", "Adrian", "Gregor", "Ingolf", "Germund", "Adelmar", "Eckard", "Raimund", "Marwin", "Dietmar"};
string germanSurname[30] = {"Loeb", "Spielberg", "Lindemann", "Frenz", "Buxbaum", "Macher", "Bacharach", "Homrighausen", "Faulhaber", "Herder", "Germar", "Eisen", "Hackl", "Specht", "Rossmann", "Erdmann", "Osterhaus", "Steinsaltz", "Spiegelmann", "Lindemann", "Kluckhohn", "Kuttner", "Seelmann", "Sattler", "Kautner", "Dunhaupt", "Scharf", "Preisner", "Werthner", "Breitner"};
string germanFemaleName[15] = {"Selina", "Isabel", "Walburg", "Berta", "Kate", "Gisela", "Amelie", "Ronja", "Karin", "Lena", "Alexandra", "Sarah", "Monica", "Kai", "Nadja"};
// NOTE: Surname is before given name in eastern nations
string easternMaleName[15] = {"Nikki", "Moronobu", "Yaichiro", "Shuncho", "Tamasaburo", "Sekien", "Kazutoshi", "Yasuhide", "Omezo", "Kinzo", "Junji", "Utamuro", "Hisaki", "Taki", "Mitsuo"};
string easternSurname[30] = {"Maki", "Shinohara", "Tsukino", "Ikeda", "Matsutoya", "Sakata", "Horiuchi", "Suda", "Tsuga", "Kawano", "Kanbayashi", "Kirigaya", "Sakimoto", "Urushido", "Inaba", "Tsukiyomi", "Saeki", "Soga", "Morioka", "Yamabe", "Nakajima", "Maruyama", "Suga", "Kamino", "Kawamoto", "Takanashi", "Ito", "Kuramoto", "Maeda", "Kanemaru"};
string easternFemaleName[15] = {"Saito", "Ane", "Fuuko", "Taji", "Isoko", "Gen", "Kuwa", "Taira", "Sachi", "Uka", "Ryoko", "Hina", "Mitsu", "Asa", "Tomie"};
// Gender Generation (Male/Female)
result = (1 + (rand() % 2));
if (result > 1) {
settlerGender = "female";
} else {
settlerGender = "male";
}
// Name and Age Generation (See Arrays)
result = (rand() % 15);
switch(nation) {
case 1: // Latin (Equal split of ages)
if (settlerGender == "male") {
givenName = latinMaleName[result];
} else {
givenName = latinFemaleName[result];
}
result = (1 + (rand() % 100));
if (result >= 66) {
settlerAge = (41 + (rand() % 30));
} else if (result > 33 || result < 66) {
settlerAge = (22 + (rand() % 41));
} else {
settlerAge = (1 + (rand() % 22));
}
result = (rand() % 30);
surName = latinSurname[result];
settlerName = givenName + " " + surName;
break;
case 2: // German (More young people)
if (settlerGender == "male") {
givenName = germanMaleName[result];
} else {
givenName = germanFemaleName[result];
}
result = (1 + (rand() % 100));
if (result >= 90) {
settlerAge = (41 + (rand() % 30));
} else if (result > 40 || result < 90) {
settlerAge = (22 + (rand() % 41));
} else {
settlerAge = (1 + (rand() % 22));
}
result = (rand() % 30);
surName = germanSurname[result];
settlerName = givenName + " " + surName;
break;
case 3: // Eastern (More older people)
if (settlerGender == "male") {
givenName = easternMaleName[result];
} else {
givenName = easternFemaleName[result];
}
result = (1 + (rand() % 100));
if (result >= 40) {
settlerAge = (41 + (rand() % 30));
} else if (result > 20 || result < 40) {
settlerAge = (22 + (rand() % 41));
} else {
settlerAge = (1 + (rand() % 22));
}
result = (rand() % 30);
surName = easternSurname[result];
settlerName = surName + " " + givenName;
break;
}
// Wealth Generation (Poor/Decent/Rich: Based on Surname)
switch(type){
case 1: // Hamlet
if (result >= 28) {
settlerWealth = "Rich";
} else if (result > 24 || result < 28) {
settlerWealth = "Decent";
} else {
settlerWealth = "Poor";
}
break;
case 2: // Village
if (result >= 26) {
settlerWealth = "Rich";
} else if (result > 19 || result < 26) {
settlerWealth = "Decent";
} else {
settlerWealth = "Poor";
}
break;
case 3: // Town
if (result >= 25) {
settlerWealth = "Rich";
} else if (result > 9 || result < 25) {
settlerWealth = "Decent";
} else {
settlerWealth = "Poor";
}
break;
case 4: // City
if (result >= 20) {
settlerWealth = "Rich";
} else if (result > 9 || result < 20) {
settlerWealth = "Decent";
} else {
settlerWealth = "Poor";
}
break;
}
}
};
Vector Initialisation and Output:
Settlement objSettlement(tempType,tempNation);
int tempNum = objSettlement.settlementQuantity;
std::vector<Settler> objSettler(objSettlement.settlementQuantity, Settler(tempType, tempNation, tempNum));
cout << "Welcome to the " << objSettlement.settlementType << " " << objSettlement.settlementName << " in the " << objSettlement.settlementNation << " nation!\n";
cout << "Featuring a population of " << objSettlement.settlementQuantity << " with " << objSettlement.settlementWealth << " wealth.\n\n";
bool repeat = true;
while (repeat == true) {
cout << "Enter the ID of a settler you would like to read about (from 0-" << (objSettlement.settlementQuantity - 1) << ", or enter 999999 to exit): ";
cin >> tempNum;
cout << "\n\n";
if (tempNum == 999999) {
repeat = false;
} else {
cout << objSettler[tempNum].settlerName << ", " << objSettler[tempNum].settlerGender << ", is " << objSettler[tempNum].settlerAge << " years old and has " << objSettler[tempNum].settlerWealth << " wealth.\n\n";
}
}
For context, "objSettlement" refers to a randomly generated Settlement instance and ".settlementQuantity" is an integer representing the settlement's population.
So, when I create a latin hamlet with 30 people, the program creates a vector with 30 cases of: "Faustus Crispian, male, is 41 years old and has Poor wealth." regardless of what number I put in from 0-29.
Why is my vector initialisation making all objects in my array the same?

Answer 1

This :
std::vector<Settler> objSettler(objSettlement.settlementQuantity, Settler(tempType, tempNation, tempNum));
creates a vector with objSettlement.settlementQuantity copies of the same object Settler(tempType, tempNation, tempNum).
Refer to this reference page for details on how the various vector constructors work.
Something like this might be closer to what you want :
std::vector<Settler> objSettler;
for (int i = 0; i < objSettlement.settlementQuantity; ++i) {
objSettler.emplace_back(tempType, tempNation, tempNum);
}

Answer 2

When you create your objSettler vector, you create one Settler randomly, which will get copied objSettlement.settlementQuantity times. In other words, your constructor is called only once and the instances in the vector are created from that one settler object using the default copy constructor.
See std::vector
For generating n random settlers, you might want to use std::generate_n and std::back_inserter:
std::vector<Settler> objSettler;
std::generate_n(std::back_inserter(objSettler),
objSettlement.settlementQuantity,
[&](){ return Settler(tempType, tempNation, tempNum); });