How do I increment an integer by the user's input in C++ within a loop and keep it incremented when the loop starts over? -

this part of code aggregate taxi program 4 taxi companies. need increment each taxi company when user adds items cart , calculate cost chosen company. program needs return main menu. thanks!

#include <iostream>     using namespace std;     int main() {     cout<<"welcome lawrence aggregation service"<< endl;     //main menu     int menu_select;     cout<< "please select following options"<< endl         << "purchase mileage vouchers from:"<< endl         << "1 - checker cab"<< endl         << "2 - gts lawrence"<< endl         << "3 - jayhawk taxi"<< endl         << "4 - redycab"<< endl         << "or"<< endl         << "5 - view cart"<< endl         << "6 - exit" << endl;     cin>> menu_select;      while ((menu_select) >=1 && (menu_select) <= 6)     {             //user's menu choice         //cab companies incrementing miles         int checker_sum;         int checker;         int gts;         int jhawk;         int redyc;          //taxi company selection         if (menu_select >= 1 && menu_select <= 4)         {             int mileage;             cout<< "how many miles purchase?"<< endl;             cin>> mileage;              //checker cab selection             if (menu_select == 1)             {                 int menu_opt;                 double price_flat;                 double price_miles;                 double mileage_cost;                 price_flat = 30.00;                 price_miles = 0.00;                 mileage_cost = mileage* price_miles + price_flat;                 checker_sum = (checker + mileage);                 cout<< "that $" <<(mileage_cost)<<                     " checker cab. thank you."<< endl<< endl;                 cout<<"you have " <<checker<< " miles checker cab."<< endl;                 }              //gts lawrence selection             else if (menu_select == 2)             {                 int menu_opt;                 double price_flat;                 double price_miles;                 double mileage_cost;                 price_flat = 5.00;                 price_miles = .20;                 mileage_cost = mileage* price_miles + price_flat;                 cout<< "that $" << mileage_cost <<                     " gts lawrence. thank you."<< endl<< endl;              }             else if (menu_select == 3)             {                 int menu_opt;                 double price_flat;                 double price_miles;                 double mileage_cost;                 price_flat = 10.00;                 price_miles = .05;                 mileage_cost = mileage* price_miles + price_flat;                 cout<< "that $" << mileage_cost <<                     " jayhawk taxi. thank you."<< endl<< endl;              }              else if (menu_select == 4)             {                 int menu_opt;                 double price_flat;                 double price_miles;                 double mileage_cost;                 price_flat = 0;                 price_miles = 1.10;                 mileage_cost = mileage* price_miles + price_flat;                 cout<< "that $" << mileage_cost <<                     " redycab. thank you."<< endl<< endl;             }         }     }     return 0; } 

for starters should declare:

int checker_sum;     int checker;     int gts;     int jhawk;     int redyc; 

outside while loop variables aren't declared multiple times

as increment mentioning create variable:

int totalcost; 

you have declare variable somewhere in main outside of of while loops. instance:

int main() {      int totalcost = 0;      cout<<"welcome lawrence aggregation service"<< endl;     //main menu     int menu_select;     cout<< "please select following options"<< endl; 

you have can change value of total cost in of loops;

once have declared is:

if (menu_select == 1)         {             int menu_opt;             double price_flat;             double price_miles;             double mileage_cost;             price_flat = 30.00;             price_miles = 0.00;             mileage_cost = mileage* price_miles + price_flat;             checker_sum = (checker + mileage);             cout<< "that $" <<(mileage_cost)<<                 " checker cab. thank you."<< endl<< endl;             cout<<"you have " <<checker<< " miles checker cab."<< endl;             totalcost = totalcost + mileage_cost             // totalcost += mileage_cost          } 

if in every loop (since declared variable outside loops) add payments make 1 variable. , when user wants view cart put:

else if(menu_select == 5) {       //whatever code want       cout << "total: " << totalcost;       //whatever code want } 

what want loop main menu put whole thing while loop:

#include<iostream>   using namespace std;   int main()  {      int totalcost = 0;      cout<<"welcome lawrence aggregation service"<< endl;      //main menu      int menu_select; while(menu_select != 6) { cout<< "please select following options"<< endl     << "purchase mileage vouchers from:"<< endl     << "1 - checker cab"<< endl     << "2 - gts lawrence"<< endl     << "3 - jayhawk taxi"<< endl     << "4 - redycab"<< endl     << "or"<< endl     << "5 - view cart"<< endl     << "6 - exit" << endl; cin>> menu_select; //user's menu choice     //cab companies incrementing miles     int checker_sum;     int checker;     int gts;     int jhawk;     int redyc; while ((menu_select) >=1 && (menu_select) <= 6) {     //taxi company selection     if (menu_select >= 1 && menu_select <= 4)     {         int mileage;         cout<< "how many miles purchase?"<< endl;         cin>> mileage;          //checker cab selection         if (menu_select == 1)         {             int menu_opt;             double price_flat;             double price_miles;             double mileage_cost;             price_flat = 30.00;             price_miles = 0.00;             mileage_cost = mileage* price_miles + price_flat;             checker_sum = (checker + mileage);             cout<< "that $" <<(mileage_cost)<<                 " checker cab. thank you."<< endl<< endl;             cout<<"you have " <<checker<< " miles checker cab."         << endl;             totalcost = totalcost + mileage_cost;             // or totalcost += mileage_cost;          }          //gts lawrence selection         else if (menu_select == 2)         {             int menu_opt;             double price_flat;             double price_miles;             double mileage_cost;             price_flat = 5.00;             price_miles = .20;             mileage_cost = mileage* price_miles + price_flat;             cout<< "that $" << mileage_cost <<                 " gts lawrence. thank you."<< endl<< endl;            totalcost = totalcost + mileage_cost;             // or totalcost += mileage_cost;          }         else if (menu_select == 3)         {             int menu_opt;             double price_flat;             double price_miles;             double mileage_cost;             price_flat = 10.00;             price_miles = .05;             mileage_cost = mileage* price_miles + price_flat;             cout<< "that $" << mileage_cost <<                 " jayhawk taxi. thank you."<< endl<< endl;             totalcost = totalcost + mileage_cost;             // or totalcost += mileage_cost;          }          else if (menu_select == 4)         {             int menu_opt;             double price_flat;             double price_miles;             double mileage_cost;             price_flat = 0;             price_miles = 1.10;             mileage_cost = mileage* price_miles + price_flat;             cout<< "that $" << mileage_cost <<                 " redycab. thank you."<< endl<< endl;             totalcost = totalcost + mileage_cost;             // or totalcost += mileage_cost;         }         else if(menu_select == 5)         {             /whatever code want            cout << "total: " << totalcost;            //whatever code want         }      } } } return 0; 

}

notice how moved the: int menu_select above while loop because if anywhere below while loop, compiler report error since using menu_select before declared.

i hope helpful , have great time coding :).