谁能帮忙看看为什么我写的con( )函数第二次调用就会死循环?第二次运行的过程中卡死在sort( )函数中的while语句中:
Lnode* sort(Lnode* L)
{
Lnode *tail, *ml, *m, *q;
m = L;
if (m != NULL){
while (m->next != NULL) //逐句检查的时候,发现第二次调用con( )时,
m = m->next; //con( )运行到sort函数时一直卡在这两句循环,但是第一次调用con( )却不会这样
}
以下是全代码(一元稀疏多项式计算器)
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
typedef struct node
{
float c; //系数
int e; //指数
int n; //项数
struct node* next;
}Lnode;
Lnode* creat(int n)
{
Lnode* L;
Lnode* tail;
tail = L = NULL;
for (int i = 0; i < n; i++) { //尾插法记录多项式数据
Lnode* p;
p = (Lnode*)malloc(sizeof(Lnode));
p->next = NULL;
printf("请分别输入第%d项的系数和指数:", i + 1);
scanf("%f %d", &p->c, &p->e);
if (i == 0) {
L = p;
tail = p;
}
else {
tail->next = p;
tail = p;
}
}
L->n = n;
Lnode* sort(Lnode * L);
sort(L);
return L;
}
void swap(Lnode* p,Lnode* q) //交换操作
{
float temp_c;
int temp_e;
temp_c = p->c; p->c = q->c; q->c = temp_c;
temp_e = p->e; p->e = q->e; q->e = temp_e;
}
Lnode* sort(Lnode* L) //降序冒泡排序
{
Lnode *tail, *ml, *m, *q;
m = L;
if (m != NULL){
while (m->next != NULL)
m = m->next;
}
tail = m;
while (tail != L){
ml = L; //ml指向最后一次交换的位置
for (m = L; m != tail; m = m->next){
q = m->next;
if (m->e < q->e){
swap(m, q);
ml = m;
}
}
tail = ml;
}
return m;
}
void disp(Lnode* L,int n)
{
Lnode* p;
p = L;
if (p == NULL)
printf("0\n\n");
else{
while (p != NULL) {
printf("%.2fX^%d ", p->c, p->e);
if (p->next != NULL) {
if ((p->next)->c >= 0)
printf("+");
}
p = p->next;
}
printf("\n");
p = L;
printf("序列形式:(%d, ", n);
while (p != NULL) {
printf("%.2f,%d", p->c, p->e);
if (p->next != NULL)
printf(", ");
p = p->next;
}
printf(")");
printf("\n\n");
}
}
void calculate(Lnode* L)
{
Lnode* p = L;
int x;
double sum = 0;
printf("请输入X的值:");
scanf("%d", &x);
while (p != NULL)
{
sum += p->c * pow(x, p->e);
p = p->next;
}
printf("当X的值为%d时,多项式的值为:%.2f\n\n", x, sum);
}
Lnode* con(Lnode* a, Lnode* b, int m) //多项式a、b求和差
{
Lnode* p, * q, *tail;
p = a; q = b; tail = p;
if (m == 4) {
Lnode* qi = q;
while (qi != NULL) {
qi->c = -qi->c;
qi = qi->next;
}
}
if (p != NULL) {
while (tail->next != NULL)
tail = tail->next;
tail->next = q;
p = sort(p);
p->n += q->n;
}
if (p == NULL && q != NULL)
p = q;
tail = p;
while (tail != NULL){ //合并同类项
if(tail->next != NULL){
if (tail->e == (tail->next)->e) {
Lnode* r = tail->next;
tail->c += r->c;
tail->next = r->next;
free(r);
p->n -= 1;
}
}
tail = tail->next;
}
return p;
free(p);
}
void select(Lnode* a, Lnode* b)
{
Lnode* c = NULL; Lnode* d = NULL;
int m;
printf("请输入数字指令:(0:退出计算器 1:计算a在X处的值 2:计算b在X处的值 3:求a+b 4:求a-b 5:计算a+b在X处的值 6:计算a-b在X处的值)\n");
scanf("%d",&m);
while (m != 0){
switch (m) {
case 1:
calculate(a);
printf("请输入下一个数字指令...\n");
scanf("%d", &m);
break;
case 2:
calculate(b);
printf("请输入下一个数字指令...\n");
scanf("%d", &m);
break;
case 3:
c = con(a, b, 3);
printf("\n多项式 a+b = ");
disp(c, c->n);
//free(c);
printf("请输入下一个数字指令...\n");
scanf("%d", &m);
break;
case 4:
d = con(a, b, 4);
printf("\n多项式 a-b = ");
disp(d, d->n);
printf("请输入下一个数字指令...\n");
scanf("%d", &m);
break;
case 5:
if (c == NULL){
c = con(a, b, 3);
printf("\n多项式 a+b = ");
disp(c, c->n);
}
calculate(c);
printf("请输入下一个数字指令...\n");
scanf("%d", &m);
break;
case 6:
if (d == NULL){
d = con(a, b, 4);
printf("\n多项式 a+b = ");
disp(d, d->n);
}
calculate(c);
printf("请输入下一个数字指令...\n");
scanf("%d", &m);
break;
default: printf("请输入正确的数字指令!\n"); break;
}
}
}
int main()
{
Lnode* a, * b; Lnode *c = NULL; Lnode* d;
int n1;
printf("请输入多项式a的项数: ");
scanf("%d", &n1);
a = creat(n1);
printf("\n多项式 a = ");
disp(a,n1);
int n2;
printf("请输入多项式b的项数: ");
scanf("%d", &n2);
b = creat(n2);
printf("\n多项式 b = ");
disp(b, n2);
c = con(a, b, 3);
printf("\n多项式 a+b = ");
disp(c, c->n);
d = con(a, b, 4);
printf("\n多项式 a-b = ");
disp(d, d->n);
//select(a, b);
return 0;
}