Question

I would like to know how to insert data into a set dynamically.
I have a text file with different points and i need to insert into the set dynamically as i will not know how many items will be there.

sample.txt

Point [3 4]
Point [5 6]

main.cpp

 set<Point> s_p2;
 if (strData.find("Point") != string::npos) {
   pos = strData.find("t");
   strData = strData.substr(pos + 2, 4);
   istringstream in(strData);
   Point temp_p;
   in >> temp_p;
   s_p2.insert(temp_p);
}

s_p2 is the set container and the following set of codes are looped till the end of the file.

Q1: If I do this, will my set have only 1 item or multiple items of temp_p?

Q2: How can i print out the values in side the set?

.

ostream& operator<<(ostream &out, Point &p2) {
    p2.setDistFrOrigin();
    out << "[" << setw(4) << p2.getX() << setw(1) << "," << setw(4) << p2.getY() << "]   " << setprecision(3) << p2.getScalarValue() << endl;
}

Answer 1

Q1: If i do this will my set have only 1 item or multiple items of temp_p

That depends. The set will only store unique Points, so if the temp_p are different each time, they will all get stored. The “uniqueness” of a Point is determined using the comparison function used for the set’s ordering.
Two elements A and B are equal if A is not greater than B and B is not greater than A.

Q2 How can i print out the values in side the set?

You should define an std::ostream& operator<<(std::ostream& os, const Point& p) operator, and then use std::cout. For example:

std::ostream& operator<<(std::ostream& os, const Point& p)
{
  return os << p.someMethod() << " " << p.someOtherMethod();
}

Then,

std::set<Point> pointSet = ....;
for (std::set<Point>::const_iterator it = pointSet.begin(); 
     it!= pointSet.end(); 
     ++it)
{
  std::cout << *it << "\n";
}

or, in c++11

for (const auto& p : pointSet)
{
  std::cout << p << "\n";
}