void DestroyPolylist(Polylist L) { Polynode *p,*q; if(L!=NULL) { p=L; while(p!=NULL) { q=p; p=p->next; free(q); } } printf("destroy"); }

这段代码实现了多项式链表的销毁功能`DestroyPolylist` 函数接收一个多项式链表 `L`，然后遍历链表，释放链表中的所有节点，并将它们所占用的内存空间归还给操作系统。具体来说，函数首先判断链表是否为空，如果不为空，就将指针 `p` 指向链表的头节点。然后遍历链表，每次释放当前节点 `q` 所占用的内存空间，并将指针 `p` 指向下一个节点。最后，函数输出一个提示信息，表示链表已经被销毁。

需要注意的是，在释放每个节点之前，必须将指针 `p` 移动到下一个节点，否则会导致内存泄漏。此外，使用 `free` 函数释放内存空间时，必须保证指针指向的内存空间是通过 `malloc` 或类似函数分配的，否则会导致未定义的行为。

相关问题

void InitPolylist(Polylist *L) {*L = (Polylist)malloc(sizeof(Polylist)); (*L)->next = NULL; } Polylist CreatePolylist()/*输入多项式的系数和指数,用尾插法建立一元多项式的链表*/ {Polylist L; Polynode *s; InitPolylist(&L); double coef; int exp; Polynode *r = L; scanf("%lf %d",&coef,&exp); while(coef != 0) { s = (Polynode *)malloc(sizeof(Polynode)); s->coef = coef; s->exp = exp; s->next = NULL; r->next = s; r = s; scanf("%lf %d",&coef,&exp); } r->next = NULL; return L; } int LengthPolylist(Polylist L) {Polylist r = L; int n = 0; while(r->next != NULL) { n++; r = r->next; } return n; } void OutputPolylist(Polylist L) { Polylist r = L->next; printf("inlcude %d coef/exp list is：\n",LengthPolylist(L)); while(r != NULL) { printf("%.2f,%d\n",r->coef,r->exp); r = r->next; } } Polylist AddPolylist()/*创建两个多项式并相加，完成后显示序列*/ {Polylist l1 = CreatePolylist(); Polylist l2 = CreatePolylist(); Polylist l3; InitPolylist(&l3); Polynode *s; Polylist r1 = l1->next, r2 = l2->next, r3 = l3; double sum; while(r1 != NULL && r2 != NULL) { s = (Polynode *)malloc(sizeof(Polynode)); if(r1->exp < r2->exp) { s->coef = r1->coef; s->exp = r1->exp; r3->next = s; r3 = s; r1 = r1->next; } else if (r1->exp == r2->exp) { sum = r1->coef + r2->coef; if(sum != 0) { s->coef = sum; s->exp = r1->exp; r3->next = s; r3 = s; r1 = r1->next; r2 = r2->next; } else { return l3; } } else { s->coef = r2->coef; s->exp = r2->exp; r3->next = s; r3 = s; r2 = r2->next; } } if(r1 != NULL){ r3->next = r1; } else { r3->next = r2; } return l3; } void ComputePolylist(Polylist L)/*计算多项式在x=%d的值*/ {Polylist r = L->next; double x = 0; double result = 0; scanf("%lf",&x); while(r != NULL) { result += r->coef * pow(x, r->exp); r = r->next; } printf("ComputePolylist in x=%.2f result is：%.2f\n",x,result); } void DestroyPolylist(Polylist L) { Polynode *p = L ,*q = L->next; while(q) { free(p); p = q; q = q->next; } free(p); printf("destroy"); } 解释一下这个代码

这段代码是一个用于处理一元多项式的链表操作程序。其中，Polylist 是一个指向 Polynode 的指针，而 Polynode 则定义了多项式中的每一个节点，包括系数和指数。程序提供了创建多项式、计算多项式值、相加多项式等功能。具体来说，CreatePolylist 函数用于输入多项式的系数和指数，用尾插法建立一元多项式的链表；AddPolylist 函数用于创建两个多项式并相加，完成后显示序列；ComputePolylist 函数用于计算多项式在给定值 x 上的值；DestroyPolylist 函数用于销毁多项式链表。该程序中的链表操作用到了常见的链表操作技巧，如链表的初始化、节点的创建、节点移动等。

#include <stdio.h> #include <malloc.h> #include <math.h> typedef struct Polynode { double coef; int exp; struct Polynode *next; }Polynode,* Polylist; Polylist H=NULL;/*一元多项式头指针的全局变量*/ /*单链表模块*/ void InitPolylist(Polylist *L); Polylist CreatePolylist(); /*输入多项式的系数和指数,用尾插法建立一元多项式的链表*/ int LengthPolylist(Polylist L); void OutputPolylist(Polylist L); Polylist AddPolylist();/*创建两个多项式并相加，完成后显示序列*/ void ComputePolylist(Polylist L);/*计算多项式在x=%d的值*/ void DestroyPolylist(Polylist L); /*注解1：形式参数Polylist L是链表的头指针*/ /*主函数模块*/ int main() { H=AddPolylist(); ComputePolylist(H); OutputPolylist(H); DestroyPolylist(H); return 0; } /* 请在这里填写答案 */ /*单链表模块*/ void InitPolylist(Polylist *L) { } Polylist CreatePolylist()/*输入多项式的系数和指数,用尾插法建立一元多项式的链表*/ { } int LengthPolylist(Polylist L) { } void OutputPolylist(Polylist L) { } Polylist AddPolylist()/*创建两个多项式并相加，完成后显示序列*/ { } void ComputePolylist(Polylist L)/*计算多项式在x=%d的值*/ { } void DestroyPolylist(Polylist L) { }补全代码

/*单链表模块*/

/*初始化链表*/
void InitPolylist(Polylist *L) {
*L = NULL;
}

/*创建一元多项式的链表*/
Polylist CreatePolylist() {
Polylist L, p, q;
int n, i;
double coef;
int exp;

InitPolylist(&L);
printf("请依次输入多项式的项数、系数和指数：\n");
scanf("%d", &n);

for (i = 0; i < n; i++) {
scanf("%lf%d", &coef, &exp);
p = (Polylist)malloc(sizeof(Polynode));
p->coef = coef;
p->exp = exp;
p->next = NULL;

if (L == NULL) {
L = p;
} else {
q = L;
while (q->next != NULL) {
q = q->next;
}
q->next = p;
}
}
return L;
}

/*计算链表的长度*/
int LengthPolylist(Polylist L) {
int len = 0;
Polylist p = L;
while (p != NULL) {
len++;
p = p->next;
}
return len;
}

/*输出链表*/
void OutputPolylist(Polylist L) {
Polylist p = L;
if (p == NULL) {
printf("多项式为空！\n");
} else {
printf("多项式的各项系数和指数分别为：\n");
while (p != NULL) {
printf("%.2lfX^%d ", p->coef, p->exp);
p = p->next;
}
printf("\n");
}
}

/*创建两个多项式并相加，完成后返回相加后的链表*/
Polylist AddPolylist() {
Polylist L1, L2, L3, p1, p2, p3, q;
InitPolylist(&L1);
InitPolylist(&L2);
InitPolylist(&L3);

printf("请输入第1个多项式：\n");
L1 = CreatePolylist();
printf("请输入第2个多项式：\n");
L2 = CreatePolylist();

p1 = L1;
p2 = L2;
p3 = L3;

while (p1 != NULL && p2 != NULL) {
q = (Polylist)malloc(sizeof(Polynode));
if (p1->exp == p2->exp) {
q->coef = p1->coef + p2->coef;
q->exp = p1->exp;
p1 = p1->next;
p2 = p2->next;
} else if (p1->exp > p2->exp) {
q->coef = p1->coef;
q->exp = p1->exp;
p1 = p1->next;
} else {
q->coef = p2->coef;
q->exp = p2->exp;
p2 = p2->next;
}
q->next = NULL;
p3->next = q;
p3 = q;
}

while (p1 != NULL) {
q = (Polylist)malloc(sizeof(Polynode));
q->coef = p1->coef;
q->exp = p1->exp;
q->next = NULL;
p3->next = q;
p3 = q;
p1 = p1->next;
}

while (p2 != NULL) {
q = (Polylist)malloc(sizeof(Polynode));
q->coef = p2->coef;
q->exp = p2->exp;
q->next = NULL;
p3->next = q;
p3 = q;
p2 = p2->next;
}

return L3;
}

/*计算多项式在x=%d的值*/
void ComputePolylist(Polylist L) {
int x;
double result = 0.0;
printf("请输入x的值：\n");
scanf("%d", &x);

Polylist p = L;
while (p != NULL) {
result += p->coef * pow(x, p->exp);
p = p->next;
}
printf("多项式在x=%d的值为：%.2lf\n", x, result);
}

/*销毁链表*/
void DestroyPolylist(Polylist L) {
Polylist p = L, q;
while (p != NULL) {
q = p->next;
free(p);
p = q;
}
}