c++链表：判断史莱姆正负，输出的正负性全是＋号

前面的部分没错，错的是//3.或//4.
输出结果如图

#include<iostream>
using namespace std;
struct Node {
    char x = ' ', y = ' ';//x存储0   y储存-或*，分别代表史莱姆和通电状况
    int d_flag = 0;//相异的flag，0是前后相同，1，反之，前后相异
    char sex = ' ';
    struct Node* next=NULL;
};
struct Node* head = NULL , * p = NULL, * r = NULL;


int main() {

    //1.输入史莱姆及其关系
    cout << "输入史莱姆0和通电情况-，输入x则停止输入"<<endl;
    char x1='y', y1='y';
    //cin >> x1 >> y1;
    head = new Node;
    r = head;
    while (x1 != 'x') {
        p = new Node;
        x1 = getchar();
        y1 = getchar();
        p->x = x1;
        p->y = y1;
        p->next = NULL;
        if(r!=NULL)
        r->next = p;
        r = p;
        
    }
    
    p = head;

    //2.通过是否通电，判断前后是否相异

    while (p->next != NULL) {
        p = p->next;
        if (p->y == '-')p->d_flag = 1;
    }

    //3.通过相异性判断正负

    p = head;
    p->next->sex = '+';
    while (p->next!= NULL) {
        
        if (p->d_flag == 1) {
            p = p->next;
            p->sex = '-';
        }
        else
            p = p->next;
            p->sex = '+';
    }

    //4.输出两种结果

    p = head;
    while (p->next != NULL) {
        //if (p->x = 'x')break;
        p = p->next;
        cout << p->sex << " ";
    }
}

修改如下，供参考：

#include<iostream>
using namespace std;
struct Node {
    char x = ' ', y = ' ';//x存储0   y储存-或*，分别代表史莱姆和通电状况
    int d_flag = 0;//相异的flag，0是前后相同，1，反之，前后相异
    char sex = ' ';
    struct Node* next = NULL;
};
struct Node* head = NULL, * p = NULL, * r = NULL;

int main() {
    //1.输入史莱姆及其关系
    cout << "输入史莱姆0和通电情况-，输入x则停止输入" << endl;
    char x1 = 'y', y1 = 'y';
    //cin >> x1 >> y1;
    head = new Node;
    r = head;
    while (1){     //(x1 != 'x') {
        if ((x1 = getchar()) == 'x')break;
        y1 = getchar();
        p = new Node;
        p->x = x1;
        p->y = y1;
        p->next = NULL;
        if (r != NULL)
            r->next = p;
        r = p;
    }
    p = head;
    //2.通过是否通电，判断前后是否相异
    while (p->next != NULL) {
        p = p->next;
        if (p->y == '-')p->d_flag = 1;
    }
    //3.通过相异性判断正负
    p = head;
    //p->next->sex = '+';
    while (p->next != NULL) {
        p = p->next;
        if (p->d_flag == 1) {
            
            p->sex = '-';
        }
        else
            //p = p->next;
            p->sex = '+';
    }
    //4.输出两种结果
    p = head;
    while (p->next != NULL) {
        //if (p->x = 'x')break;
        p = p->next;
        cout << p->sex << " ";
    }
}