Question

(Coding done in c++, Virtual Studio) Having a problem with the line trying to compare the date of birth.
           **fall.sort(compare_DOB); //Here lies your error**

#include <fstream>
#include <iostream>
#include <string>
#include <list>
#include <cctype>
using namespace std;
const char THIS_TERM[] = "fall.txt";
const string HEADER = "\nWhat do you want to do ?\n\n"
"\t. Add a new friend name and DOB ? \n"
"\t. Edit/Erase a friend record ? \n"
"\t. Sort a Friend's record ? \n"
"\t. View all in memory at present ? \n"
"\t. Update file with data currently in memory ? \n"
"\t. Load in data from file ? \n"
"\t. exit program ? ";
class Friend
{public:
   Friend(string nam, string num)
   {setName(nam);
       setDOB(num);}
   void setName(string nam) { name = nam; }
   void setDOB(string num) { DOB = num; }
   string getName() { return name; }
   string getDOB() { return DOB; }
private:
   string name, DOB;};
list< Friend >::iterator existDOB(list < Friend >& term, string& DOB)
{list< Friend >::iterator it;
   for (it = term.begin(); it != term.end(); ++it)
   {if (it->getDOB() == DOB)
           return it;}
   return term.end();}
int newFriend(list< Friend >& term)
{cout << "\nEnter an empty record to exit this 'Input Loop' ..." << endl;
   int count, reply;
   string nam, num;
   for (;; )
   {cout << "\nDOB : ";
       getline(cin, num);
       cout << "Name : ";
       getline(cin, nam);
       if (nam == "" || num == "")
           break;
       cout << "Add or Redo (a/r) ? ";
       reply = cin.get();
       cin.sync();
       if (toupper(reply) != 'A')
       {cout << "Aborted ..." << endl;
           continue;}
       term.push_back(Friend(nam, num));
       ++count;
       cout << "Added ..." << endl;}
   return count;}
void viewFriend(list< Friend >& term)
{list< Friend >::iterator it;
   int i = 0;
   for (it = term.begin(); it != term.end(); ++it)
   {cout << ++i << ".\n"
           << "Name : " << it->getName() << endl
           << "Date of Birth : " << it->getDOB() << endl;}}
int fileFriend(list< Friend>& term)
{ofstream fout(THIS_TERM);
   if (!fout)
   {cout << "\nError attempting to open file ..." << endl;
       return -1;}
   list< Friend >::iterator it;
   int i = 0;
   for (it = term.begin(); it != term.end(); ++it)
   {fout << it->getName() << "," << it->getDOB() << endl;
       ++i;}
   fout.close();
   if (i == (int)term.size())
       cout << "\nAll " << i << " records filed ok." << endl;
   else
       cout << "\nOnly " << i << " of " << term.size()
       << " records were written ..." << endl;
   return i;}
int readFriend(list < Friend >& term)
{ifstream fin(THIS_TERM);
   if (!fin)
   {cout << "Error attempting to open file ... "
           << "(Perhaps it dosen't exist yet?)" << endl;
       return -1;}
   if (term.size()) // i.e. if not == ...
   {cout << "\nDo you want over-write the " << term.size()
           << " records in memory (y/n) ? " << flush;
       int reply = toupper(cin.get());
       cin.sync();
       if (reply != 'Y')
       {cout << "Aborted ... " << flush;
           return 0;}}
   list< Friend>temp;
   term = temp;
   string nam, num;
   int i;
   for (i = 0; getline(fin, nam, ','); ++i)
   {getline(fin, num, '\n');
       term.push_back(Friend(nam, num));}
   fin.close();
   return i;}
bool editFriend(list< Friend>& term)
{cout << "\nEnter an empty record to exit this 'Edit/Erase Function' ..."
       << "\nEnter the DOB of the Friend's record to edit ? " << flush;
   string DOBStr, nam;
   getline(cin, DOBStr);
   list< Friend >::iterator i;
   list< Friend >::iterator index;
   i = existDOB(term, DOBStr);
   if (i == term.end())
   {cout << "This '" << DOBStr << "' does not exist." << endl;
       return false;}
   cout << "Name : " << i->getName() << endl
       << "DOB : " << i->getDOB() << endl
       << "Ok to edit/erase (y/n) ? " << flush;
   int reply = toupper(cin.get());
   cin.sync();
   if (reply != 'Y')
   {cout << "Aborted ... " << endl;
       return false;}
   cout << "\nDo you want to erase this record (y/n) ? " << flush;
   reply = toupper(cin.get());
   cin.sync();
   if (reply == 'Y')
   {   term.erase(i);
       cout << "Erased ..." << endl;
       return true;   }
   cout << "\nNew DOB : ";
   getline(cin, DOBStr);
   index = existDOB(term, DOBStr);
   if (index != term.end() && index != i)
   {   cout << "\nThat " << DOBStr << " already exits ... " << endl;
       return false;}
   cout << "New Name : ";
   getline(cin, nam);
   if (nam == "" || DOBStr == "")
       return false;
   cout << "Ok or Redo (o/r) ? ";
   reply = cin.get();
   cin.sync();
   if (toupper(reply) != 'O')
   {   cout << "Aborted ..." << endl;
       return false;}
   i->setName(nam);
   i->setDOB(DOBStr);
   cout << "Edited ..." << endl;
   return true;}
void pauseForEnter()
{cout << "\nPress 'Enter' to continue ... " << flush;
   cin.sync();
   cin.get();}
int main()
{list <Friend > fall;
   int count = readFriend(fall);
   if (count >= 0)
       cout << count << " Friend's record(s) read into memory ..." << endl;
   else
       cout << "(The file will be created when some Friend's records exist.)"
       << endl;
   bool changes = false;
   int reply;
   for (;; )
   {cout << HEADER;
       reply = toupper(cin.get());
       cin.sync();
       if (reply == ' ' || reply == 'A')
       {int new_Friend = newFriend(fall);
           cout << endl << new_Friend << " Friend's record(s) added ..."
               << " The total number of Friend's records now is "
               << fall.size() << endl;
           if (new_Friend)
               changes = true;   }
       else if (reply == ' ' || reply == 'E')
       {if (editFriend(fall))
               changes = true;   }
       else if (reply == ' ' || reply == 'S')
       {cout << "\nSort by DOB? " << flush;
           reply = toupper(cin.get());
           cin.sync();
           cout << "Now sorted in memory by ";
           if (reply == 'I')
           {   fall.sort(compare_DOB); //Here lies your error
               cout << "DOB. ";   }
           cout << "Update file (y/n) ? " << flush;
           reply = toupper(cin.get());
           cin.sync();
           if (reply == 'Y')
           {changes = true;
               cout << "File to be updated ...\n";   }       }
       else if (reply == ' ' || reply == 'V')
           newFriend(fall);
       else if (reply == ' ' || reply == 'U')
       {   if (!changes)
               cout << "\nNo changes to file ..." << endl;
           else
           {   cout << "Are you sure you want to update the file (y/n) ? "
                   << flush;
               reply = toupper(cin.get());
               cin.sync();
               if (reply == 'Y')
               {if (fileFriend(fall) != (int)fall.size())
                       cout << "\nERROR! NOT all records were filed!" << endl;
                   else
                   {   changes = false;
                       cout << "File write operation confirmed." << endl;   }               }           }       }
       else if (reply == ' ' || reply == 'L')
       {   int condition = readFriend(fall);
           if (condition >= 0)
               cout << "\nThere were " << condition
               << " Friend's records read into memory from file." << endl;}
       else if (reply == ' ' || reply == 'X')
       {   if (changes)
               fileFriend(fall);
           break;   }
       else
       {cout << "\nThis choice not implemented yet ... " << endl;}}
   string tmpSee = " ";
   tmpSee = "notepad" + tmpSee + THIS_TERM;
   system(tmpSee.c_str());}

Answer 1

Edited Code that works without errors is as follows-
Edited Code has been hightlightd.

#include <fstream>
#include <iostream>
#include <string>
#include <list>
#include <cctype>
using namespace std;
const char THIS_TERM[] = "fall.txt";
const string HEADER = "\nWhat do you want to do ?\n\n"
"\t. Add a new friend name and DOB ? \n"
"\t. Edit/Erase a friend record ? \n"
"\t. Sort a Friend's record ? \n"
"\t. View all in memory at present ? \n"
"\t. Update file with data currently in memory ? \n"
"\t. Load in data from file ? \n"
"\t. exit program ? ";
class Friend
{public:
Friend(string nam, string num)
{setName(nam);
setDOB(num);}
void setName(string nam) { name = nam; }
void setDOB(string num) { DOB = num; }
string getName() { return name; }
string getDOB() { return DOB; }
private:
string name, DOB;};
list< Friend >::iterator existDOB(list < Friend >& term, string& DOB)
{list< Friend >::iterator it;
for (it = term.begin(); it != term.end(); ++it)
{if (it->getDOB() == DOB)
return it;}
return term.end();}
int newFriend(list< Friend >& term)
{cout << "\nEnter an empty record to exit this 'Input Loop' ..." << endl;
int count, reply;
string nam, num;
for (;; )
{cout << "\nDOB : ";
getline(cin, num);
cout << "Name : ";
getline(cin, nam);
if (nam == "" || num == "")
break;
cout << "Add or Redo (a/r) ? ";
reply = cin.get();
cin.sync();
if (toupper(reply) != 'A')
{cout << "Aborted ..." << endl;
continue;}
term.push_back(Friend(nam, num));
++count;
cout << "Added ..." << endl;}
return count;}
void viewFriend(list< Friend >& term)
{list< Friend >::iterator it;
int i = 0;
for (it = term.begin(); it != term.end(); ++it)
{cout << ++i << ".\n"
<< "Name : " << it->getName() << endl
<< "Date of Birth : " << it->getDOB() << endl;}}
int fileFriend(list< Friend>& term)
{ofstream fout(THIS_TERM);
if (!fout)
{cout << "\nError attempting to open file ..." << endl;
return -1;}
list< Friend >::iterator it;
int i = 0;
for (it = term.begin(); it != term.end(); ++it)
{fout << it->getName() << "," << it->getDOB() << endl;
++i;}
fout.close();
if (i == (int)term.size())
cout << "\nAll " << i << " records filed ok." << endl;
else
cout << "\nOnly " << i << " of " << term.size()
<< " records were written ..." << endl;
return i;}
int readFriend(list < Friend >& term)
{ifstream fin(THIS_TERM);
if (!fin)
{cout << "Error attempting to open file ... "
<< "(Perhaps it dosen't exist yet?)" << endl;
return -1;}
if (term.size()) // i.e. if not == ...
{cout << "\nDo you want over-write the " << term.size()
<< " records in memory (y/n) ? " << flush;
int reply = toupper(cin.get());
cin.sync();
if (reply != 'Y')
{cout << "Aborted ... " << flush;
return 0;}}
list< Friend>temp;
term = temp;
string nam, num;
int i;
for (i = 0; getline(fin, nam, ','); ++i)
{getline(fin, num, '\n');
term.push_back(Friend(nam, num));}
fin.close();
return i;}
bool editFriend(list< Friend>& term)
{cout << "\nEnter an empty record to exit this 'Edit/Erase Function' ..."
<< "\nEnter the DOB of the Friend's record to edit ? " << flush;
string DOBStr, nam;
getline(cin, DOBStr);
list< Friend >::iterator i;
list< Friend >::iterator index;
i = existDOB(term, DOBStr);
if (i == term.end())
{cout << "This '" << DOBStr << "' does not exist." << endl;
return false;}
cout << "Name : " << i->getName() << endl
<< "DOB : " << i->getDOB() << endl
<< "Ok to edit/erase (y/n) ? " << flush;
int reply = toupper(cin.get());
cin.sync();
if (reply != 'Y')
{cout << "Aborted ... " << endl;
return false;}
cout << "\nDo you want to erase this record (y/n) ? " << flush;
reply = toupper(cin.get());
cin.sync();
if (reply == 'Y')
{ term.erase(i);
cout << "Erased ..." << endl;
return true; }
cout << "\nNew DOB : ";
getline(cin, DOBStr);
index = existDOB(term, DOBStr);
if (index != term.end() && index != i)
{ cout << "\nThat " << DOBStr << " already exits ... " << endl;
return false;}
cout << "New Name : ";
getline(cin, nam);
if (nam == "" || DOBStr == "")
return false;
cout << "Ok or Redo (o/r) ? ";
reply = cin.get();
cin.sync();
if (toupper(reply) != 'O')
{ cout << "Aborted ..." << endl;
return false;}
i->setName(nam);
i->setDOB(DOBStr);
cout << "Edited ..." << endl;
return true;}
void pauseForEnter()
{cout << "\nPress 'Enter' to continue ... " << flush;
cin.sync();
cin.get();}

bool compare_DOB(Friend a, Friend b){
   return(a.getDOB()<b.getDOB());
}

int main()
{list <Friend > fall;
int count = readFriend(fall);
if (count >= 0)
cout << count << " Friend's record(s) read into memory ..." << endl;
else
cout << "(The file will be created when some Friend's records exist.)"
<< endl;
bool changes = false;
int reply;
for (;; )
{cout << HEADER;
reply = toupper(cin.get());
cin.sync();
if (reply == ' ' || reply == 'A')
{int new_Friend = newFriend(fall);
cout << endl << new_Friend << " Friend's record(s) added ..."
<< " The total number of Friend's records now is "
<< fall.size() << endl;
if (new_Friend)
changes = true; }
else if (reply == ' ' || reply == 'E')
{if (editFriend(fall))
changes = true; }
else if (reply == ' ' || reply == 'S')
{cout << "\nSort by DOB? " << flush;
reply = toupper(cin.get());
cin.sync();
cout << "Now sorted in memory by ";
if (reply == 'I')
{ fall.sort(compare_DOB); //Here lies your error
cout << "DOB. "; }
cout << "Update file (y/n) ? " << flush;
reply = toupper(cin.get());
cin.sync();
if (reply == 'Y')
{changes = true;
cout << "File to be updated ...\n"; } }
else if (reply == ' ' || reply == 'V')
newFriend(fall);
else if (reply == ' ' || reply == 'U')
{ if (!changes)
cout << "\nNo changes to file ..." << endl;
else
{ cout << "Are you sure you want to update the file (y/n) ? "
<< flush;
reply = toupper(cin.get());
cin.sync();
if (reply == 'Y')
{if (fileFriend(fall) != (int)fall.size())
cout << "\nERROR! NOT all records were filed!" << endl;
else
{ changes = false;
cout << "File write operation confirmed." << endl; } } } }
else if (reply == ' ' || reply == 'L')
{ int condition = readFriend(fall);
if (condition >= 0)
cout << "\nThere were " << condition
<< " Friend's records read into memory from file." << endl;}
else if (reply == ' ' || reply == 'X')
{ if (changes)
fileFriend(fall);
break; }
else
{cout << "\nThis choice not implemented yet ... " << endl;}}
string tmpSee = " ";
tmpSee = "notepad" + tmpSee + THIS_TERM;
system(tmpSee.c_str());}

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