Question

Whats wrong with it? its supposed to sort it in ascending order. it doesn’t cause the program to crash but when I’m pretty sure theres something wrong because when I the linked list to other functions it gets stuck in an infinite loop.

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

struct dataTag {
   int key;
};

struct nodeTag {
   struct dataTag data;
   struct nodeTag *pNext;
};
typedef struct dataTag dataStructType;
typedef struct nodeTag nodeStructType;

nodeStructType *SortList(nodeStructType *pFirst)
{
    nodeStructType *swap,*ptr;
    if(pFirst == NULL)
        return NULL;
    else
    {
        swap = pFirst;
        ptr = pFirst -> pNext;
        while(ptr != NULL)
        {
            if(ptr -> data.key < swap -> data.key)
                swap = ptr;
            ptr = ptr -> pNext;
        }
        swap -> pNext = SortList(pFirst -> pNext);
        return swap;
    }
}
int main(void)
{
   nodeStructType *pFirst;
   /* Lets say codes exists here that makes a link list etc just to make the code short*/
   pFirst = SortList(pFirst);
   /*Free List*/
   return 0;
}

Answer 1

You cant just swap nodes to sort the list. Here is a link to a program that sorts singly linked lists.

Basically the line
swap = ptr;
will not work as you think. You need to reset the links appropriately to ensure that your linked list remains linked correctly.