Question

在下面的程序中，我尝试按升序对人员列表进行排序。但是，我遇到了分段错误，我不知道如何更改程序以获得预期的结果。有什么建议吗？

 #include <stdio.h>
    #include <stdlib.h>
    /* these arrays are just used to give the parameters to 'insert',
       to create the 'people' array 
    */

    #define HOW_MANY 7
    char *names[HOW_MANY]= {"Simon", "Suzie", "Alfred", "Chip", "John", "Tim",
                  "Harriet"};
    int ages[HOW_MANY]= {22, 24, 106, 6, 18, 32, 24};

    typedef struct person
    {
      char *name;
      int age;
      struct person *next;
    }Person;
    static int compare_people(Person *p1, Person *p2)
    {     
      return strcmp(p1->name, p2->name);
    }

    static Person* insert_sorted(Person *headp, char *name, int age) 
    {
      Person *p = malloc(sizeof(Person)); 
      if (p == NULL)
        abort();
      p->name = name;
      p->age = age;
      if (headp == NULL)
      {
        headp = p;
        return p;
      }
      else
      {
        Person *current = headp;
        Person *temp =NULL;
        while(current != NULL && compare_people(current, p) < 0)
        {
          temp = current;
          if(compare_people(current,p) > 0)
           break;
          current = current->next;
       }
        p->next = current; 
        temp->next = p;
       return headp;
      }

    }  
    int main(int argc, char **argv) 
    {
      Person *people2 = NULL;
      for (int i = 0; i < 7; i++) 
      {
        people2 = insert_sorted(people2, names[i], ages[i]);
        //printf ("name: %s, age: %i\n", people2->name, people2->age);
      }

      while(people2 != NULL)
      {
        printf ("name: %s, age: %i\n", people2->name, people2->age);
        people2 = people2->next;
      }
      return 0;
    }

Answer 1

对于初学者，最好按以下方式定义函数compare_people

static int compare_people( Person *p1, Person *p2 )
{     
    return strcmp( p1->name, p2->name ) < 0;
}

至于insert_sorted那么循环中的条件

    while(current != NULL && compare_people(current, p) < 0)
    {
      temp = current;
      if(compare_people(current,p) > 0)
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       break;
      current = current->next;
   }

没有意义，因为如果条件为真，那么while循环的当前迭代最初将不会被执行，因为循环的条件是

compare_people(current, p) < 0

这些条件相互矛盾。

当节点被添加到空列表时，您忘记将数据成员next设置为NULL。

使用您的方法可以按以下方式编写函数

static int compare_people( Person *p1, Person *p2 )
{     
    return strcmp( p1->name, p2->name ) < 0;
}

static Person* insert_sorted( Person *headp, char *name, int age) 
{
    Person *p = malloc( sizeof( Person ) ); 

    if ( p == NULL ) abort();

    p->name = name;
    p->age  = age;

    if ( headp == NULL || compare_people( p, headp ) )
    {
        p->next = headp; 
        headp = p;
    }
    else
    {
        Person *current = headp;

        while ( current->next != NULL && !compare_people( p, current->next ) )
        {
            current = current->next;
        }

        p->next = current->next; 
        current->next = p;
    }

    return headp;
}

Answer 2

（1）需要#include <string.h>

（2）您忘记初始化成员的next。

p->name = name;
p->age = age;
p->next = NULL;//<--this 
if (headp == NULL)
{
    headp = p;
    return p;
}

（3）temp NULL

时不予考虑

更改

p->next = current;
temp->next = p;

到

p->next = current; 
if(temp)
    temp->next = p;
else
    headp = p;

链表以C排序

2 个答案: