#include <iostream>
#include <iomanip>
#include <vector>

using namespace std;

//-----------------------------------------------------------------------
// Example code that creates a container, puts some strings in it,
// and then tries to delete them.
// Lessons: 
//  (1) Be careful trying to modify a container you're iterating on.
//  (2) (Very unlike C,) C++ supports full container operations, like
//      assignment and comparison
//-----------------------------------------------------------------------

//-------------------------------------------------------
// Helper function to print container contents
//-------------------------------------------------------
template <class T>
void dumpContainer(const T c) {
  for (auto &el : c) {
    cout << el << ' ';
  }
  cout << endl;
}

//-------------------------------------------------------
// Copy b to a
//-------------------------------------------------------
template <class T>
void reset(T &a, const T &b) {
  // Container assignment does full contents copy
  a = b;
}

//-------------------------------------------------------
// mainline
//-------------------------------------------------------
int main(int argc, char *argv[]) {

  vector<string> stringVec = {"one", "two", "three", "four"};
  cout << "Original vector contents:" << endl;
  dumpContainer(stringVec);

  //---------------------------------------------------------
  // Create (and preserve) a copy of the container.
  // Copy constructor makes a deep copy.
  //---------------------------------------------------------
  auto copy = stringVec;  // (copy constructor invocation)

  //--------------------------------------------------------------------------
  // Note that the equality operator here actually compares container contents
  //--------------------------------------------------------------------------
  cout << "copy == stringVec? " << (copy == stringVec ? "yes" : "no") << endl;

  cout << endl << "Now try to erase all elements that begin with 't':" << endl;

  //---------------------------------------------------------------
  // Modifying a container you're iterating on is risky -- sometimes
  // it's okay, and sometimes it's a fatal error.
  //---------------------------------------------------------------

  //---------------------------
  // 1st try - naive approach
  //---------------------------
  for ( auto it = stringVec.begin(); it != stringVec.end(); it++ ) {
    if ( (*it)[0] == 't' ) stringVec.erase(it);
  }
  cout << setw(20) << "First try result: ";
  dumpContainer(stringVec);

  //---------------------------
  // 2nd try - use updated iterator returned by erase()
  //---------------------------
  reset(stringVec, copy);
  for ( auto it = stringVec.begin(); it != stringVec.end(); it++ ) {
    if ( (*it)[0] == 't' ) it = stringVec.erase(it);
  }
  cout << setw(20) << "Second try result: ";
  dumpContainer(stringVec);

  //---------------------------
  // 3rd try - correct!
  //---------------------------
  reset(stringVec, copy);
  auto it = stringVec.begin();
  while ( it != stringVec.end() ) {
    if ( (*it)[0] == 't' ) it = stringVec.erase(it);
    else it++;
  }
  cout << setw(20) << "Third try result: ";
  dumpContainer(stringVec);

  return 0;
}