using Math::Round with visual c++ in vs2008

Question

I have the following visual c++ code

#include <iostream>
#include <string>
#include <sstream>
#include <math.h>

using namespace std;

int Main()
{
    double investment = 0.0;
    double newAmount = 0.0;
    double interest = 0.0;
    double totalSavings = 0.0;
    int month = 1;
    double interestRate = 0.065;

    cout << "Month\tInvestment\tNew Amount\tInterest\tTotal Savings";
    while (month < 10)
    {
            investment = investment + 50.0;
     if ((month % 3 == 0))
     {
       interest = Math::Round((investment * Math::Round(interestRate/4, 2)), 2);
     }
     else
     {
       interest = 0;
     }
     newAmount = investment + interest;
     totalSavings = newAmount;
     cout << month << "\t" << investment << "\t\t" << newAmount << "\t\t" << interest << "\t\t" << totalSavings;
     month++;
    }
  string mystr = 0;
  getline (cin,mystr);
  return 0;
}

But its giving me problems using Math::Round, truly I don't know how to use this function using visual c++

Answer 1

AFAICT cmath (math.h) doesn't define a Round function, nor a Math namespace. see http://msdn.microsoft.com/en-us/library/7wsh95e5%28VS.80,loband%29.aspx

Answer 2

Unfortunately Math::Round is part of the .NET framework and is not part of the normal C++ spec. There are two possible solutions to this.

The first is to implement the round function yourself, using either ceil or floor from <cmath> and creating a function similar to the following.

#include <cmath>
inline int round(float x) { return (floor(x + 0.5)); }

The second is to enable Common Language Runtime (CLR) support for your C++ program, which will allow access to the .NET framework, but at the cost of having it no longer be a true C++ program. If this is just a small program for your own use, this probably isn't a big deal.

To enable CLR support, do the following:

Right click your solution and click properties. Then click Configuration Properties -> General -> Project Defaults. Under Common Language Runtime support, choose the option Common Language Runtime Support (/clr). Then click Apply and OK.

Next, add the following to the top of your code:

using namespace System;

Now you should be able to use Math::Round as with any other .NET language.

Answer 3

Math::Round() is .NET, not C++.

I don't believe there is a direct equal in C++.

You can write your own like this (untested):

double round(double value, int digits)
{
  return floor(value * pow(10, digits) + 0.5) / pow(10, digits);
}

Answer 4

You might be better off adding 0.5 and using floor() as mentioned in another post here to get basic rounding.