C++, hogy indítom újra automatikusan?

Ha nem szépen akarod csinálsz egy pl.:main2() függvényt, még mielőtt a fő maint-t bezárnád.Így is megoldhatod:

int a,b,c;

double num1;

string key;

char choise,equals;

cin >> a;

cin >> choise;

switch (choise){

case '+':

cin >> c;

cout << "=" << a+c << endl;

break;

case '-':

cin >> c;

cout << "=" << a-c << endl;

break;

case '*':

cin >> c;

cout << "=" << a*c << endl;

break;

case '/':

cin >> c;

cout << "=" << a/c << endl;

break;

case '2':

num1 = pow(a,2.0);

cout << "=" << num1;

break;

case '3':

num1 = sqrt (a);

cout << "=" << num1;

break;

}

int a2,b2,c2;

double num12;

string key2;

char choise2,equals2;

cin >> a2;

cin >> choise2;

switch (choise2){

case '+':

cin >> c;

cout << "=" << a+c << endl;

break;

case '-':

cin >> c2;

cout << "=" << a-c << endl;

break;

case '*':

cin >> c;

cout << "=" << a2*c2 << endl;

break;

case '/':

cin >> c;

cout << "=" << a/c << endl;

break;

case '2':

num1 = pow(a,2.0);

cout << "=" << num1;

break;

case '3':

num12 = sqrt (a2);

cout << "=" << num12;

break;

}