convert from c++ to c# code

Question

#include <iostream>

#include <fstream>

#include <bits/stdc++.h>

using namespace std;

struct node

{

string stock_code;

string stock_name;

double amt_invested;

int shares_held;

double current_price;

struct node *next;

struct node *prev;

};

int main()

{

ifstream infile("input.txt");

string sc,sn;

double ai,cp;

int sh;

int flag = 0;

struct node* head1 = NULL;

struct node* head2 = NULL;

while (infile >> sc >> sn >> ai >> sh >> cp)

{

// cout << sc << " " << sn << " " << ai << " " << sh << " " << cp << endl;

if(flag == 0)

{

struct node* temp = (struct node*)malloc(sizeof(struct node));

temp->stock_code = sc;

temp->stock_name = sn;

temp->amt_invested = ai;

temp->shares_held = sh;

temp->current_price = cp;

//cout << "ho" << endl;

temp->prev = NULL;

temp->next = NULL;

head1 = temp;

temp = (struct node*)malloc(sizeof(struct node));

temp->stock_code = sc;

temp->stock_name = sn;

temp->amt_invested = ai;

temp->shares_held = sh;

temp->current_price = cp;

temp->prev = NULL;

temp->next = NULL;

head2 = temp;

flag++;

}

temp->prev = NULL;

temp->next = NULL;

head1 = temp;

temp = (struct node*)malloc(sizeof(struct node));

temp->stock_code = sc;

temp->stock_name = sn;

temp->amt_invested = ai;

temp->shares_held = sh;

temp->current_price = cp;

temp->prev = NULL;

temp->next = NULL;

head2 = temp;

flag++;

}

}

}