C语言 请帮忙看看这个问题

#include <stdio.h>
#include "malloc.h"

typedef struct polyn
{

float coef;
int expn;
struct polyn* next;

} L_node,*Link_list;

Link_list Pa,Pb;

void CreatPolyn ( )
{
Link_list p,q;
int expn;
float coef;//int coef，修改定义为浮点数

p = ( Link_list ) malloc ( sizeof( L_node ) );

Pa = p,q=p;

scanf("%f,%d",&coef,&expn); //%d改为%f

if(coef == 0) printf("the Polyn is not exist!");

while( coef )
{

p = ( Link_list ) malloc ( sizeof( L_node ) );

q->next =p;

p->coef = coef;

p->expn = expn;
q=p;//这句关键，要指向最新的节点，否则将无法形成链表

scanf("%f,%d",&coef,&expn);

}

p->next = NULL;
}

void display_Polyn ( Link_list p )
{

while((p->next)!=NULL) //这里改一下，因为最后一个节点的next已经是NULL，