design a simple program to calculate arithematic function

#include <iostream>
#include <cmath>
#include <ccomplex>
#include <complex>void calculate();
namespace pi{


    doubleconst pi = 3.1415926535897932384626433832795; 


}
namespace e{

doubleconst e = 2.718;


}
usingnamespace std;


int main(){

    char options;
    char choose;
    double num1,num2;
    double sum = 0;
begin:

    cout << "Welcome to my calculator" << endl << "To calculate press C for help H and to exit E." << endl;
    cin >> options;
    if (options = 67){ 
    do
    {
calc:
        cout << "Enter a x value" << flush;
        cin >> num1;
        cout << "Enter a y value" << flush;
        cin >> num2;

        cout << "Choose your operator" << endl << "1)+,-,*,/;" << endl << "2)sqr,sqrt"<< endl << "3)sin,cos,tan" << endl << "4)sinh,cosh,tanh" << endl << "5)Constants" << endl;
        cin >> choose;
        switch (choose)
        {
        case43:
            {
            sum = num1 + num2;
            cout << num1  << "+" << num2 << "=" << sum << endl;
            }
            break;
        case45:
            {
            
                sum = num1 - num2;
                cout << num1 << "-" << num2 << "=" << sum << endl;


            }
            break;
        case42:
            {
            
                sum = num1 * num2;
                cout << num1 << "*" << num2 << "=" << sum << endl;

            }
            break;
        case47:
            {
            
                if(num2 == 0){
                
                    cout << "Invalid" << endl;
                
                }
                else{
                
                    sum = num1 / num2;
                    cout << num1 << "/" << num2 << "=" << sum  << endl;

                }

            }
            break;
        case83:
            sum= num1 * num1;
            cout << num1    << "  on squared is  " <<   sum << endl;
            break;
        case81:
            sum = sqrt(num1);
            cout << "The squared root of   " << num1 << "   is equal to  " << sum << endl;
            break;
        case113:
            sum = sqrt(num1);
            cout << "The squared root of   " << num1 << "   is equal to  " << sum << endl;
            break;
        case115:
            sum= num1 * num1;
            cout << num1    << "  on squared is  " <<   sum << endl;
            break;
        case84:
            sum = tan(num1);
            cout << "The tangent of  " << num1 << "  is  " << sum << endl;
            break;
        case79:
            sum = cos(num1);
            cout << "The cosine of " << num1 << "  is  " << sum << endl;
            break;
        case73:
            sum = sin(num1);
            cout << "The sine of " << num1 << "  is  " << sum << endl;
        case53:
            cout <<"The value of PI is   " << pi::pi << endl << "The value of Euler's constant is  " << e::e << endl; 
        default:

            cout << "Operator does not exist" << endl; 

            
        }
        
        cout << "Do you want to exit or do more calculations" << endl;
        cin >> options;
        

    } while ((choose != '+') && (choose != '-') && (choose != '*') && (choose = '/') );
 }
    switch(options){ 
    
    case67:
        goto calc;
        break;
    case69 :
        abort();
        break;
    case72:
        cout <<"This is a scientific calculator.It has basic operations,advanced operations.As you would expect for the basic operations it is their signs,but for the advanced goes " <<endl
            << "Geometry funtions:sin-I,cos-O and the tan-T;(all functions must be uppercase letters)." << endl << 
            "For functions:sqr-S,sqrt-Q;(uppercase letters)"<< endl;
        goto begin;
        break;
    }

    system("pause");
    cin.get();
    return0;
}