Program to make simple calculator

Exercise 1)

Write a program and call it calc.cpp which is the basic calculator and receives three values from input via keyboard.

 The first value as an operator (Op1) should be a char type and one of (+, -, *, /, s) characters with the following meanings:

o ‘+’ for addition (num1 + num2)

o ‘-’ for subtraction (num1 - num2)

o ‘*’ for multiplication (num1 * num2)

o ‘/’ for division (num1 / num2)

o ‘s’ for swap

 Program should receive another two operands (Num1, Num2) which could be float or integer.

 The program should apply the first given operator (Op1) into the operands (Num1, Num2) and prints the relevant results with related messages in the screen.

 Swap operator exchanges the content (swap) of two variables, for this task you are not allowed to use any further variables (You should use just two variables to swap).

#include<iostream>
#include<cmath.h>

using namespace std;

int main()
{
//-------defining variables and initializing them-------------    
    double num1,num2;
    char operation,redo;
//--------Printing my name on screen----------------    
    cout<<"Welcome to the calculater program v.1.0 written by Your Name"<<endl;
    cout<<"***************************************************************"<<endl;
    cout<<endl<<endl<<endl;
//--here do loop is used so that the program can be used more then one time
//without exiting the run screen---------------------------    
    do
    {
 //----receiving the variables from input--------------         
    cout<<" Please enter an operation which you like to calculate (+,-,*,/,s)";
    cout<<"[s stands for swap]:";
    cin>>operation ;
    cout<<endl<<endl;
     cout<<" Please enter two numbers to apply your requested operation(";
    cout<<operation<<"):"<<endl<<"1st num:";
    cin>>num1;
    cout<<"2nd num:" ;
    cin>>num2;
    cout<<endl;
 //---used switch function so thet the operater can be decided------------  
    switch (operation)
    {
//------calculating the requested equation for inputs------------- 
//-------at the same time printing the results on screen-----------          
     case'+':            
             cout<<"The addition of two numbers ("<<num1<<","<<num2<<"):";
             cout<<num1+num2<<endl;
             break; 
     case'-':
             cout<<"The substraction of two numbers ("<<num1<<","<<num2<<"):";
             cout<<num1-num2<<endl;
             break;
      case'*':
             cout<<"The multiplication of two numbers ("<<num1<<","<<num2<<"):";
             cout<<num1*num2<<endl;
             break;
      case'/':
             cout<<"The division of two numbers ("<<num1<<","<<num2<<"):";
             if(num2==0)
             {
             cout<<"not valid"<<endl;
             }
             cout<<(num1/num2)<<endl;
             break;
      case's':
             cout<<"The swap of two numbers ("<<num1<<","<<num2<<"):";
             swap(num1,num2);
             cout<<"1stnumber="<<num1<<"and 2nd number="<<num2<<endl<<endl;                    
           break;
      default:
              cout<<"unknown command"<<endl;
      
           }
 //----now once again the program will ask the user if want to continue or not          
           cout<<"enter y or Y to continue:";
           cin>>redo;
           cout<<endl<<endl;
           }
           while(redo=='y'||redo=='Y');
           
   system("pause");
    return 0;
    
    }