Sorting linked list with multiple elements

Rather than pass around double star pointers (e.g. Contact **start), I prefer a separate List struct. This can be [easily] be expanded for a doubly linked list.

Also, I always pass a struct to a function with a pointer. Passing by value [as you're doing when creating the list] is slower. And, in the general case would cause a stack overflow if the struct was large (e.g. it had an element: int data[10000000];)

I had some difficulty understanding your sorting logic. And, using traverse->next->next seems problematic to me. I couldn't tell exactly what your sorting algorithm was based on. I'm guessing it was trying to do an insertion sort [but I could easily be wrong].

I'm more familiar with mergesort for linked lists that pull from source lists and append to a destination list during the merge phase. That would be fast(er), and it adapts well to linked lists.

But, rather than get that far afield from your code, I adapted some of the logic from that to create a selection sort [I think].

Anyway, here's the refactored code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX 50

typedef struct Contact {
    char name[MAX];
    char number[MAX];
    char address[MAX];
    char email[MAX];
    struct Contact *next;
} Contact;

typedef struct {
    Contact *head;
} List;

void
create_linkedList(List *list, Contact *p)
{
    Contact *new = malloc(sizeof(Contact));

    strcpy(new->name, p->name);
    strcpy(new->number, p->number);
    strcpy(new->address, p->address);
    strcpy(new->email, p->email);

    new->next = list->head;
    list->head = new;
}

void
printList(List *list)
{
    Contact *cursor = list->head;

    printf("List:\n");
    while (cursor != NULL) {
        printf("  %s\n", cursor->name);
        cursor = cursor->next;
    }
}

void
sorting(List *list)
{
    Contact *oldhead = list->head;
    Contact *newhead = NULL;
    Contact *newprev = NULL;

    while (oldhead != NULL) {
        // lowest element to be selected
        Contact *bestcur = oldhead;
        Contact *bestprev = NULL;

        // find the lowest element in remaining list
        Contact *travprev = NULL;
        Contact *travcur = oldhead;
        for (;  travcur != NULL;  travcur = travcur->next) {
            if (strcasecmp(bestcur->name,travcur->name) > 0) {
                bestcur = travcur;
                bestprev = travprev;
            }
            travprev = travcur;
        }

        // remove selected element from old list
        if (bestprev != NULL)
            bestprev->next = bestcur->next;
        else
            oldhead = bestcur->next;

        bestcur->next = NULL;

        // append to new list
        if (newprev != NULL)
            newprev->next = bestcur;
        else
            newhead = bestcur;
        newprev = bestcur;
    }

    list->head = newhead;
}

int
main(void)
{
    FILE *file = fopen("contacts.csv", "r");

    if (file == NULL)
        return 1;

    Contact person;
    List *list = calloc(1,sizeof(*list));

    // Loop inside csv file til' the end of file
    while (fscanf(file, "%[^,], %[^,], %[^,], %[^\n] ",
        person.name, person.number, person.address, person.email) == 4) {
        // Skip header file from csv
        if (strcmp("NAME", person.name) == 0)
            continue;

        create_linkedList(list, &person);
    }

    printList(list);

    // Swapped
    sorting(list);

    printList(list);

    return 0;
}