sort struct array in c++

Question

I have an array of a Struct and trying to sort them alphabetically by lname ,i tried bubble sort but when we have some empty items in our array bubble sort won't work correctly .so is there any function to sort these items ?

This is my code :

#include<iostream>
#include<algorithm>

using namespace std;


struct user {

char lname[30];
int userid;
};

user libuser[1000];

int main(){


strcpy(libuser[0].lname,"");
libuser[0].userid = 0;


strcpy(libuser[1].lname,"backzade");
libuser[1].userid = 1;

strcpy(libuser[2].lname,"akhondali");
libuser[2].userid = 2;

    strcpy(libuser[3].lname,"sayidian");
libuser[3].userid = 3;

    strcpy(libuser[4].lname,"navah");
libuser[4].userid = 4;

    strcpy(libuser[5].lname,"mostarab");
libuser[5].userid = 5;


libuser[6].userid = 0;


    strcpy(libuser[7].lname,"");
libuser[7].userid = 0;

    strcpy(libuser[8].lname,"");
libuser[8].userid = 0;

    strcpy(libuser[9].lname,"borobaba");
libuser[9].userid = 9;

    strcpy(libuser[10].lname,"divune");
libuser[10].userid = 10;



for(int i=1;i<1000;i++)
    if(libuser[i].userid!=0)
        cout<<libuser[i].lname<<"\n";


system("PAUSE");

return 0;
}

Answer 1

This code just can be one method among many good methods. I just use std::sort and lambda. I hope this will help you a little. Happy new year!

std::sort (std::begin(libuser), std::end(libuser), [&](const user& first, const user& second) -> bool
{
    return (first.lname[0] < second.lname[0]); 
});

Answer 2

#include <iostream>
#include <algorithm>

using namespace std;

struct user
{
    char lname[30];
    int userid;
};

user libuser[1000];
int elementCount = 0;

int main()
{
    strcpy(libuser[0].lname,"");
    libuser[0].userid = 0;

    strcpy(libuser[1].lname,"backzade");
    libuser[1].userid = 1;

    strcpy(libuser[2].lname,"akhondali");
    libuser[2].userid = 2;

    strcpy(libuser[3].lname,"sayidian");
    libuser[3].userid = 3;

    strcpy(libuser[4].lname,"navah");
    libuser[4].userid = 4;

    strcpy(libuser[5].lname,"mostarab");
    libuser[5].userid = 5;

    libuser[6].userid = 0;

    strcpy(libuser[7].lname,"");
    libuser[7].userid = 0;

    strcpy(libuser[8].lname,"");
    libuser[8].userid = 0;

    strcpy(libuser[9].lname,"borobaba");
    libuser[9].userid = 9;

    strcpy(libuser[10].lname,"divune");
    libuser[10].userid = 10;

    //sort
    for(int i = 0; i < 1000; i++)
    {
        for(int j = 0; j < 1000 - 1; j++)
        {
            if(strcmp(libuser[j].lname, libuser[j + 1].lname) > 0)  //change to < 0 for descending sort
            {
                user temp = libuser[j];
                libuser[j] = libuser[j + 1];
                libuser[j + 1] = temp;
            }
        }
    }


    for(int i = 1; i < 1000; i++)
    {
        if(libuser[i].userid!=0)
        {
            cout<<libuser[i].lname<<"\n";
        }
    }


    system("PAUSE");

    return 0;
}