cout << "Pick a number." << endl;
cin >> choice;
bool numberWasFound = false;

int j;

for (j = 0; sortedCollection.size(); j++)
{
   if(sortedCollection[j] == choice)
   {
      numberWasFound = true;
   }      
}   
   
if(numberWasFound == true)
{
   cout << "At index: " << j << endl;
}
else if (numberWasFound == false)
{
   cout << "Not found" << endl;
}