Thread: help needed with simple code

Hi my code is working except the final part where I test whether the sum of probabilities is equal 1 or not. I am new in this field and I guess that is the reasson I just cannot find any mistake. Th euser needs to enter 3 numbers which sum is one. And if they enetr it wrongly, teh program should let them know.

I would really appreciate any help!!!!!
#include <iostream.h>
#include <fstream.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>

Code:

main ()
{

ofstream os;
ifstream is;

os.open("d:\\Branka\\lit review\\programming\\Prep\\intro.txt");
  if(os.fail())
  { 
          cout << " Output file opening failed. \n";
          exit(1);
  }

 os.setf(ios::fixed);
 os.setf(ios::showpoint);
 os.precision(3);  

int a;
float num;
float sum=0;
float small=1e-2; 

 cout <<"\nPlease enter the probability values for RIF1 or Training for recovery within the team/ATC Centre.";
 cout <<"\nThere are three possible Levels of influence of this paricular RIF.";
 cout <<"\nYou need to enter corresponding probabilities for each Level so that the sum equals one (e.g. 0.33, 0.33, 0.33).";
 cout <<"\nIf one Level corresponds precisely to the event under description, simply enter zero to the other boxes (e.g. 0, 1, 0 or 0.5, 0, 0.5).";
 cout <<"\nPlease enter three values separarted with the space: "; 
 
for (a=0; a<3; a++) 
                     
       {
       cin >> num;
       os <<"The RIF Level "; os  << (a+1); os << " is: "; os << num; os << endl;
       sum +=num;
        }
        
if ((sum>=1.00-small)&&(sum<=1.00+small))
       {cout << "The input is verified, move on to the next RIF!\n";}
   else   
       {cout << " The sum of your inputs is not 1, but"; cout << sum; 
        cout << "! Input the probabilities so that their sum equals 1.\n";}
         
os << "The sum of your inputs is "; os << sum; os << endl;


return 0;
 }