Problems in sorting element inside an array of object.

[Saim_5]

i have initialized the elements of the array by reading the strings from a file, however when I call the sort function, either the program crashes or it just outputs NULL. What could be a more efficient way to store data from a file?

the file that I have opened contains the following text:
"
ppp zaeem na2 lun
pti farea na1 balla

"

#include <iostream>
#include <string>
#include <stdlib.h>
#include <Conio.h>
#include <cstdlib>
#include <string>
#include <string.h>
#include <cstring>
#include <fstream>
using namespace std;

class candidate
{
public:
    string party;
    string name;
    string constituency;
    string symbol;

    candidate()
    {
        party = "";
        name = "";
        constituency = "";
        symbol = "";
    }
};

candidate *candi = new candidate[3];
int size = 0;

void read_into_array()
{
    int i = 0;
    string name, party, consti, symb;
    ifstream a("new.txt");
    if (!a)
        cout << "file not found." << endl;
    else
    {

        a >> party >> name >> consti >> symb;
        while (!a.eof())
        {   

            candi[i].party = party;
            candi[i].name = name;
            candi[i].constituency = consti;
            candi[i].symbol = symb;
            a >> party >> name >> consti >> symb;

            size++;
            i++;
        }
        a.close();
    }
}
class voter
{
public:
    void show_all_candidates()
    {
        for (int i = 0; i < size; i++)
        {
            cout << "Candidate's Name:  " << candi[i].name << endl;
            cout << "Candidate's Constituency:  " << candi[i].constituency << endl;
            cout << "Candidate's Party'" << candi[i].party << endl;
            cout << "Party Symbol:  " << candi[i].symbol << endl;
        }
    }

    void sort_by_name()
    {
        for (int i = 1; i < size; i++)
        {
            for (int j = 1; j <size-i; j++)
            {
                string temp=" ";
                if (candi[j].name > candi[j + 1].name)
                {

                    temp=candi[j].name;
                    candi[j].name = candi[j + 1].name;
                    candi[j + 1].name = temp;

                    temp=candi[j].constituency;
                    candi[j].constituency = candi[j + 1].constituency;
                    candi[j + 1].constituency = temp;

                    temp=candi[j].party;
                    candi[j].party = candi[j + 1].party;
                    candi[j + 1].party = temp;

                    temp=candi[j].symbol;
                    candi[j].symbol = candi[j + 1].symbol;
                    candi[j + 1].symbol = temp;
                }
            }
        }
    }
};

int main()
{
    voter obj_voter;

    read_into_array();
    obj_voter.sort_by_name();
    obj_voter.show_all_candidates();
   // obj_voter.sort_by_name();
}

[Schol-R-LEA]

Before I address the question, allow me to trim the includes list a bit, removing some which are either redundant or not actually valid under standard C++ :

#include <iostream>
#include <cstdlib>
#include <string>
#include <cstring>
using namespace std;

Mind you, using using namespace std; isn't a great idea either, since it essentially undermines the whole point of having a std namespace in the first place, but for homework it is at least acceptable.

As for the actual question, the first thing I take note of is that there looks to be two off-by-one errors in the sorting algorithm.

        for (int i = 1; i < size; i++)  // should be 'i=0'
        {
            for (int j = 1; j <size-i; j++) // should be 'j=0'
            {

Arrays in C++ are zero-indexed, meaning that the first element of the array arry is arry[0], the second is arry[1], and so forth to arry[size-1]. These off-by-one errors could be the source of the segfaults, though I would have to take a closer look than I have to be certain.

[jwenting]

start by using the standard containers.
https://www.cplusplus.com/reference/list/list/sort/ shows exactly what to do...

That's the c++ way.

[xrjf]

Try renaming size, for example sz.

[Jim_532]

You might try somthing like this....

struct some_struct 
    { 
           int value; 
    } arr[100]; 

    bool sort_fn(some_struct a, some_struct b) 
    { 
            return (a.value < b.value); 
    } 

    main() 
    { 
            std::sort(arr, arr+len, sort_fn); 

}