Program calculator di C++

Saya sudah membuat program calculator tapi input user hanya bisa dalam bentuk x+y (tapi ada option yg bisa membuat calculation baru di loop) saya ingin user input bisa dalam bentuk seperti ini x+y-z*s, dengan kata lain lebih dari 2 variable; Ini yg saya buat :

#include #include using namespace std;

double result(double XX,char calCulate,double XY){ double Result; if(calCulate=='+'){Result = (XX += XY);} else if(calCulate=='-'){Result = (XX -= XY);} else if(calCulate=='/'){Result =(XX /= XY);} else if (calCulate=='*'){Result=( XX *= XY);} else{ cout << "Invalid Input (if an error has occured please quit the program\n"; } return Result; }

int main(){ char userInput; cout << "*************** Calculator ****************\n"; cout << "AVAILABLE CALCULATIONS =\n + (addition)\n"; cout<< "-(substraction)\n"; cout << "/(division) \n"; cout << "*(multification)\n\n"; cout << "please type c to start new calculation and q to exit\n\n\n ## Please note that you can only enter 2 values " << endl; cout<<"Please type c to start or Any other key to quit"<&gt; Starter; bool StartOrNo; if(Starter=='c'){ StartOrNo=true; } else{ StartOrNo=false; } while(StartOrNo){ for (int i=0;i<=99;i++){ double XX; double XY; char calCulate; if(i<=98){ cout << "Please enter the equation (e.g.1+1)"<&gt; XX; cin >> calCulate; cin >> XY; cout << "="<< result(XX,calCulate,XY)<&gt; userInput; if(userInput=='q'){ break; } else if(userInput=='c')i++; else{ cout << "Invalid input\n"; break; } } else if(i==99){ cout << "Too much input\n\n"<