Problems with linked lists ~~~ Urgent ~~~

aoaksm

Create two linked lists (A, B), then join them and sort them from low to high
Debugging under VC + 6.0, the LINK function jumps out when running. F11 observes that the HEAD returned by the function twice points incorrectly, but I don't know what is wrong ~
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
#define NAMELEN 10
#define LEN sizeof (struct data)
typedef
struct data
{
           long num;
           char name [NAMELEN];
           struct data * next;
};
struct data * Crt (void)
{
           int count = 1;
           struct data * head, * fwd;
           head = fwd = (struct data *) malloc (LEN);
           head-> num = -1;
           do
           {
                       fwd = head-> next = (struct data *) malloc (LEN);
                       printf ("Stu% -4d\n", count ++);
                       printf ("Num =>");
                       scanf ("% ld",&fwd-> num);
                       printf ("Name =>");
                       scanf ("% s",&fwd-> name);
           }
           while (fwd-> num);
           return (head);
}
void link (struct data * A_head, struct data * B_head)
{
           struct data * fwd = A_head;
           fwd = fwd-> next;
           while (fwd-> next)
                       fwd = fwd-> next;
           fwd-> next = B_head;
}
void ord (struct data * head)
{
           struct data * fwd, * flw, * ord;
           ord = fwd = flw = head;
           fwd = fwd-> next;
           while (ord-> next)
           {
                       if (fwd-> num <ord-> num)
                       {
                                   flw-> next = fwd-> next;
                                   fwd-> next = ord-> next;
                                   ord = ord-> next = fwd;
                       }
                       flw = fwd;
                       fwd = fwd-> next;
           }
}
void print (struct data * fwd)
{
           int count = 1;
           fwd = fwd-> next;
           while (fwd)
           {
                       printf ("Stu% -4d\n", count ++);
                       printf ("Num% -4d\n", fwd-> num);
                       printf ("NAME% s\n", fwd-> name);
                       fwd = fwd-> next;
           }
}
void main ()
{
           void link (struct data * A_head, struct data * B_head);
       void ord (struct data * head);
       void print (struct data * fwd);
           struct data * A_head, * B_head;
           printf ("Input infomations of Group A students\n");
           A_head = Crt ();
           printf ("Input infomations of Group B students\n");
           B_head = Crt ();
           printf ("Now link Group A and Group B\n");
           link (A_head, B_head);
           printf ("Finally, order the new Group\n");
           ord (A_head);
           printf ("Now check the result\n");
           print (A_head);
}

冷夜星光

It seems that at the time of creation, fwd = head-> next = (struct data *) malloc (LEN); there is a problem here

aoaksm

Thank you ~ It is indeed here, it has been found out ~