Простой калькулятор и калькулятор с парсингом

#include <iostream>
#include <cmath>
 
using namespace std;
int main()
{
 
float a, b, s;
int dp;
cout << "Калькулятор" << endl;
cout << "1 сложение" << endl;
cout << "2 вычитание" << endl;
cout << "3 Умножение" << endl;
cout << "4 деление" << endl;
cout << "5 квадратный корень из числа" << endl;
cout << " Введите число a и b " << endl;
cin >> dp;
cin >> a;
cin >> b;
 
 switch(dp)
{
case 1:
cout << " число a = " << a << endl;
cin >> a;
cout << "число b = " << b << endl;
cin >> b;
s = a + b;
cout << "\n" << a << " + " << b << " = " << s << endl;
break;
case 2:
cout << " число a = " << a << endl;
cin >>a;
cout << "число b = " << b << endl;
cin >> b;
s = a - b;
 cout << "\n" << a << " - " << b << " = " << s << endl;
break;
case 3:
cout << "число a = " << a << endl;
cin >>a;
cout << "число b = " << b << endl;
cin >> b;
s = a * b;
 cout << "\n" << a << " * " << b << " = " << s << endl;
break;
case 4:
cout << "число a = " << a << endl;
cin >>a;
cout << "число b = " << b << endl;
cin >> b;
s = a / b;
 cout << "\n" << a << " * " << b << " = " << s << endl;
break;
case 5:
cout << "число a = " << a << endl;
cin >> a;
s = sqrt(a);
cout << "\n" << "корень из a = " << s << endl;
break;
} 
return 0;
}