convertion

[ProgramMaster]

Alright so I want to have the data entered and then during the next two steps I want the string data to be turned into int then double but I cant figuer out how to do it I have tried atoi and atof but when i do it nothing happens

 #include <iostream>
#include <string>

using namespace std;

string Udata;

void divider(), divider2(), divider3();
void welcome();
string getInput();

int main ()
{
	

  for (int i = 0; i < 3; i++)
  {
	  if( i == 0)
	  {
		  divider();
		  getInput();
		  cout << Udata <<endl;
		  
		  system("pause");
	  }
	  else if (i == 1)
	  {
		  divider2();
		  getInput();
		  cout<<"two" << endl;
		    char buffer[256];
 
  fgets (buffer, 256, stdin);
  Udata = atoi (buffer);
  printf ("The value entered is %d. Its double is %d.\n",Udata);
		  
		  system("pause");
	  }
	  else if(i == 2)
	  {
		  divider3();

		  cout<< "one" << endl;
		  
		  system("pause");
	  }
  }

}


void divider()
{
	cout <<  "\n****************  GET NAME ****************" << endl;
}

void divider2()
{
	cout <<  "\n****************  GET AGE ****************" << endl;
}

void divider3()
{
	cout <<  "\n****************  GET MILEAGE ****************" << endl;
}


}

string getInput()
{
	getline(cin,Udata);
	return Udata;
}

[MiiNiPaa]

http://en.cppreference.com/w/cpp/string/basic_string/stol
http://en.cppreference.com/w/cpp/string/basic_string/stof

[ProgramMaster]

Thank you thats help alot ^^