C++, где я могу поставить утверждение в классе или объекте для подтверждения рождения и смерти населения

Question

Мне нужно проверить мои Population, birth и death, в моей программе. Я хочу, чтобы Population всегда начинал и никогда не позволял идти ниже 2. Для birth и death Я никогда не хочу, чтобы они были меньше 0. Как выполнить эту задачу? Если вам нужно какое-либо разъяснение, я могу предоставить. Я новичок на этом сайте.

#include <iostream> 
#include <cmath> 
#include <iomanip> 
#include <string> 
using namespace std; 



class Population 
{ 
private: 
    int current_pop; 
    int Births; 
    int annuel_births; 
    int deaths; 
    int annuel_deaths; 
public: 

    void setpop(int); 
    int getpop(int); 
    void setborn(double); 
    void setdead(double); 
    double getdead(float deaths, int current_pop) 
    { 
     return deaths/current_pop; 
    }; 
    double getborn(float Births, int current_pop) 
    { 
     return Births/current_pop; 
    }; 
}; 
void menu(); 
void Population::setpop(int people) 
{ 

    current_pop = people; 
    if (people < 2) 
    { 
     people = 2; 
    } 
} 
int Population::getpop(int people) 
{ 
    return current_pop; 
} 

void Population::setborn(double baby) 
{ 
    Births = baby; 
    if (baby < 0) 
    { 
     baby = 0; 
    } 
} 

void Population::setdead(double dead) 
{ 
    deaths = dead; // i tried to add the validation here but it still allows me to change it //below 0 same thing with the other validations 
    if (dead < 0) 
    { 
     dead = 0; 
    } 

} 

int main() 
{ 
    double Births = 0; 
    double Deaths = 0; 
    int people = 2; 
    Population location; 
    char choice; 

    cout << "Welcome to the population program.\nPlease select one of the menu items by entering a value 1-8. \n1 . Enter population, Annuel Births, Annuel Deaths.\n2 . Change Population.\n3 . Change Annuel Births.\n4 . Change annuel Deaths.\n5 . View current Population.\n6 . View Birthrate.\n7 . View DeathRate. \n8 . exit program." << endl; 

    do 
    { 
     const char Max_Choice = '8'; 
     char getChoice(char); 
     choice = getChoice(Max_Choice); 
     switch (choice) 
     { 
     case '1': cout << "This is the town of Kakariko Village.\nPlease input the current population: "; cin >> people; 

      cout << "input the annuel number of births: "; cin >> Births; 
      cout << "input the annuel deaths in this village: "; cin >> Deaths; 
      cout << "==========================================" << endl; 
      menu(); 
      char getChoice(char); 
      break; 

     case '2': cout << "ok you wish to change population!\nThis is the town of Kakariko Village.\nPlease input the current population: "; cin >> people; 
      cout << " " << endl; 
      menu(); 
      char getChoice(char); 
      location.setpop(people); // calling function with variable as argument 
      cout << "current populaion = " << people << endl; 
      break; 
     case '3': cout << "you wish to change the number of annuel births\ninput the annuel number of births: "; cin >> Births; 
      location.setborn(Births); 
      cout << "your birthrate is: " << Births << endl; 
      cout << " " << endl; 
      menu(); 
      char getChoice(char); 
      break; 

     case '4': cout << "ok you wish to change the annuel number of deaths\ninput the annuel deaths in this village: "; cin >> Deaths; 
      location.setdead(Deaths); 
      cout << " your death rate is: " << Deaths << endl; 
      cout << " " << endl; 
      menu(); 
      char getChoice(char); 
      break; 
      location.setpop(people); 
     case'5': cout << "ok you wish to view population it's: " << people << endl; 
      break; 

     case'6':cout << "ok you wish to view the birthrate it's: " << location.getborn(Births, people) << endl; 
      cout << " " << endl; 
      menu(); 
      char getChoice(char); 
      break; 

     case'7':cout << "ok you wish to view the deathrate it's: " << location.getdead(Deaths, people) << endl; 
      cout << " " << endl; 
      menu(); 
      char getChoice(char); 
      break; 
     case'8': 
       return 0; 
      break; 

     } 
    } while (choice != '8'|| choice != '1'); cin >> choice; 

    system("pause"); 
    return 0; 
} 



char getChoice(char max) 
{ 
    char choice = cin.get(); 
    cin.ignore(256, '\n'); 
    cin.clear(); 
    while (choice < '1' || choice > max) 
    { 
     cout << "choice must be between 1 and " << max << ". " 
      << "enter choice again.: "; choice = cin.get(); 
     cin.ignore(); 
    } 
    return choice; 


} 

void menu() 
{ 
    cout << "Please select one of the menu items by entering a value 1-8. \n1 . Enter population, Annuel Births, Annuel Deaths.\n2 . Change Population.\n3 . Change Annuel Births.\n4 . Change annuel Deaths.\n5 . View current Population.\n6 . View Birthrate.\n7 . View DeathRate. \n8 . exit program." << endl; 
} 

Answer 1

Проверьте функцию setDead()

void Population::setdead(double dead) 
{ 
    deaths = dead; 
    // i tried to add the validation here but it still allows me to change it 
    //below 0 same thing with the other validations 
    if (dead < 0) // ??? 
    { 
     dead = 0; // ??? 
    } 
} 

Вы на самом деле изменения аргумента функции, в то время как вы должны проверить элемент данных вашего класса.