Calculator using IOSTREAM

[prog_tom]

#include <iostream>
#include <string>
using namespace std;
string thename;
float thenum;
float thenum2;
float thenum3;
void addfunc(float a, float b,float c);

int main()
{
    cout<<"Welcome to the math world!!!\n\n\n\n"<<endl;
	addfunc(thenum,thenum2,thenum3);
	cout<<"\n\n\n\n*************HTTP://WWW.MERLINPAL.COM************\n\n"<<endl;

	return 0;

}

void addfunc(float a,  float b,float c)
{
	cout<<"Number1\n"<<endl;
	cin>>thenum;
	cout<<"Number2\n"<<endl;
	cin>>thenum2;
	cout<<"Number3\n"<<endl;
	cin>>thenum3;
	a=thenum;
	b=thenum2;
	c=thenum3;
	int thewhole=a+b+c;
	cout<<"\n\n\nToltal:     "<<thewhole<<endl;
}