Question

I have a data text file which contains this

Map2D, [3, 2]
Dot3D, [25, -69, -33], [-2, -41, 58]
Map3D, [6, 9, -50]
Map2D, [3, 2]
Dot3D, [7, -12, 3], [9, 13, 68]
Map3D, [6, 9, 5]
Map2D, [3, 2]
Dot3D, [70, -120, -3], [-29, 1, 268]
Dot3D, [7, 12, 3], [-9, 13, 68]
Map3D, [1, 3, 8]
Dot2D, [5, 7], [3, 8]

Basically the text file first data is the class name which i got 4 class

Map2D
Map3D
Dot2D
Dot3D

I was trying to write my own file manipulator so that my program can extract the data above and overload the extraction operator >> for each of the 4 class and then storing it into relevant object.

I was thinking of using vector, map, set or list to store . but for this how do i achieve what i want to do such as store into relevant object of the class.

I tried googling around on how to create my own file manipulator, but will be good if someone could show me some sample code and i can compile and execute it maybe in a test file then observe the output myself. I would like to use iomanip to do a overload on the >> operator

I have to use manipulator because i need create something like

I need to do something like

cout << "Input File Name";
cin >> readFile;

and perform all the data reading & object creation

I am sorry for all the trouble caused. then it will read the records line by line, then create the class and also the data in it.

Thanks for all your help!

Answer 1

This is an example with std::cin. It should work just fine with a fstream. parsing your input is really nasty. Is it possible to remove the brackets(“[” amd “]”) from the input?

#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <algorithm>
#include <c>

class Map2D {
    std::vector<int> values;
public:
    friend std::istream& operator>>(std::istream& in, Map2D m) {
        std::string i;
        in >> i;
        std::stringstream ss(i);
        std::getline(ss, i, '[');
        std::getline(ss, i, ',');
        ss >> i;
        std::cout << i << std::endl;
        in >> i;
        ss.str("");
        ss << i;
        i = i.substr(0, i.size()-1);
        ss >> i;
        std::cout << i << std::endl;;
    }
};

int main() {
    std::string type, file_name;
    std::cout << "Input File Name";
    std::cin >> file_name;
    std::fstream file(file_name.c_str());
    Map2D m;
    while (std::getline(std::cin, type, ',')) {
        if(type.find("Map2D") != std::string::npos) {
            file >> m;
        }
    }
}