#include <iostream>#include <string>#include <fstream>#include <list>using namespace std;struct triangle {  double x1,y1,z1;  double x2,y2,z2;  double x3,y3,z3;  string color;};typedef vector<triangle> triangles;// The standard library container will do the memory management for you.// Yes, it's good to know how to do this stuff, but it's better to practice that// by designing your *own* classes for *unique* purpose. You can also try// learning by *reading* your compiler's std library implementations (but be// warned that the variable names usually suck).// I prefer to put functions in order - declaration before use - within the// implementation file. Of course, in a header you still need to declare// all "public" functions anyway, but by doing it this way, you save typing,// and also highlight circular dependencies in the functions (by the fact// that you will be *forced* to declare one in order to compile).// As a helper function for get_tris(), I implement an operator overload that// reads a single triangle.istream& operator>>(istream& is, triangle& tri) {  return is >> tri.x1 >> tri.y1 >> tri.z1            >> tri.x2 >> tri.y2 >> tri.z2            >> tri.x3 >> tri.y3 >> tri.z3            >> tri.color >> ws;}triangles get_tris() {  triangles result;  triangle current;  ifstream tri_file("sphere.tri");  while (tri_file >> current) {    // That will implicitly check if the file is open, because the first read    // would fail otherwise.    result.push_back(current);  }  // You can actually do better, using std::copy from the <algorithm> header; \  // I will show that upon request.  return result;}// Passing by reference allows you the functionality acheived by "passing by// pointer" in C, without all the manual referencing and dereferencing (either// at the call site or in the implementation).void print_tris(const triangles& v) {  cout << "\n\n\n";  int count = 0;  for (triangles::iterator it = v.begin(); it != v.end(); ++it) {    // The iterator provides a pointer-like interface, accessing elements of    // the vector in turn.    cout << "Vector number " << ++count << " is "         << it->x1 << ' ' << it->y1 << ' ' << it->z1 << '\t'         << it->x2 << ' ' << it->y2 << ' ' << it->z2 << '\t'         << it->x3 << ' ' << it->y3 << ' ' << it->z3 << '\t'         << '\n';  }}// You can actually "do better" with the algorithm header, again, although for // a code snippet this short the benefit isn't really realized. The idea is// to create an operator overload to output a single triangle, and then use the// same approach as for the reading, specifying 'cout' as an output stream.// However, that requires that you treat this as the definitive way of// "outputting a triangle", which may not be what you want (e.g. if you later// implement saving of triangles that were modified in your program). In that// case, you could make use of std::for_each() instead.int main() {  // You should initialize variables to their first value, whenever that value  // is determined by a known expression (i.e., isn't set by using the variable  // as an out-parameter).  triangles start = get_tris();  print_tris(start);  // But note that you don't even need a variable here, since the memory  // management disappeared and thus there is only one call upon the vector.  // You could equivalently write: print_tris(get_tris());  // Anyway, as a special case, you don't need to return 0 from main(). This is  // defined behaviour in the standard - falling off the end of main implicitly  // returns 0, although it wouldn't for other functions. Anyway, my style  // generally favours omitting things that do no work and don't imply anything  // that couldn't easily be inferred, so I never write it myself.}