Question

下面我有一些代码可以创建一个单链表，并在其中存储一些点。它编译，但对于我的生活，我不知道我在哪里以及为什么我会遇到分段错误。它在程序启动时就会发生。

另外，在你告诉我之前，我知道这个排序链表算法的效率非常低，但我一直试图让它工作一段时间，而我只是想在这一点上努力工作。

非常感谢您的帮助！

文件1：

#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include "point.h"

typedef struct node
{
    Point p;
    struct node *next;
} node;

void insertAtFront(node **start, Point *ip);
void sort(node *start);
void swap(node *a, node *b);
void printList(node *start);

int main(int argc, char **argv)
{
    Point *insertPoint;
    node *head = NULL;

    point_set(insertPoint,7.0,1.0);
    insertAtFront(&head,insertPoint);
    sort(head);

    point_set(insertPoint,1.0,1.0);
    insertAtFront(&head,insertPoint);
    sort(head);

    point_set(insertPoint,4.0,1.0);
    insertAtFront(&head,insertPoint);
    sort(head);

    point_set(insertPoint,3.0,1.0);
    insertAtFront(&head,insertPoint);
    sort(head);

    printList(head);
}

void insertAtFront(node **start, Point *ip)
{
    node *node1 = (node*)malloc(sizeof(node));
    node1->p = *ip;
    node1->next = *start;
    *start = node1;
}

void sort(node *start)
{
    Point *tp1 = malloc(sizeof(Point));
    Point *tp2 = malloc(sizeof(Point));
    int swapped;
    node *node1;
    node *node2 = NULL;
    double d1;
    double d2;
    if(node1 == NULL)
        return;
    do
    {
        swapped = 0;
        node1 = start;
        *tp1 = node1->p;
        *tp2 = node1->next->p;
        d1 = distanceFromOrigin(tp1);
        d2 = distanceFromOrigin(tp2);
        while(node1->next != node2)
        {
            if(d1 > d2)
            {
                swap(node1,node1->next);
                swapped = 1;
            }
            node1 = node1->next;
        }
        node2 = node1;
    }
    while(swapped);
}

void swap(node *a, node *b)
{
    Point *tp;
    *tp = a->p;
    a->p = b->p;
    b->p = *tp;
}

void printList(node *start)
{
    node *temp = start;
    Point *tp = malloc(sizeof(Point));
    printf("\n");
    while(temp != NULL)
    {
        *tp = temp->p;
        printf("Point: (%g,%g) - Distance: %g", point_getX(tp), point_getY(tp), distanceFromOrigin(tp));
        temp = temp->next;
    }
}

文件2：

#include <assert.h>
#include <stdio.h>
#include "point.h"
#include <math.h>

void point_translate(Point *p, double x, double y)
{
    point_set(p,(point_getX(p)+x),(point_getY(p)+y));
}

double point_distance(const Point *p1, const Point *p2)
{
    double temp1 = (point_getX(p1) - point_getX(p2));
    double temp2 = (point_getY(p1) - point_getY(p2));
    double temp3 = (temp1*temp1)+(temp2*temp2);
    double dist = sqrt(temp3);
    return dist;
}

double distanceFromOrigin(const Point *p1)
{
    double x = point_getX(p1);
    double y = point_getY(p1);
    double temp = (x*x)+(y*y);
    double dist = sqrt(temp);
    return dist;
}

文件3：

#ifndef _POINT_H_
#define _POINT_H_

typedef struct Point 
{
  double x;
  double y;
} Point;

void point_translate(Point *p, double x, double y);
double point_distance(const Point *p1, const Point *p2);
double distanceFromOrigin(const Point *p1);

static inline double point_getX(const Point *p)
{
  return p->x;
}
static inline double point_getY(const Point *p)
{
  return p->y;
}
static inline Point *point_set(Point *p, double x, double y)
{
  p->x = x; 
  p->y = y;
  return p;
}



#endif

Answer 1

好的，一开始就是正确的：

int main(int argc, char **argv)
{
   Point *insertPoint;   // this pointer points nowhere
   node *head = NULL;

   point_set(insertPoint,7.0,1.0);   // still point_set dereferences it

我的分段错误发生在哪里？ C

1 个答案: