C結構指針作爲參數：對結構進行永久更改

此代碼嘗試按優先級排序一系列節點，事情是，我從函數返回來排序節點，我所做的任何事情都沒有堅持。以下是我的簡單代碼，後面跟着輸出。C結構指針作爲參數：對結構進行永久更改

#include <stdio.h> 
#include <stdlib.h> 
#define null 0 

typedef struct NODE{ 
    struct NODE * next; 
    struct NODE * prev; 
    int priority; 
}NODE; 

struct NODE nodes[5]; 

struct NODE * head = null; 

NODE * function(NODE * pHead, NODE * top){ 

    NODE * pos = top; 

    if(top == null){ 
     top = pHead; 
    } 
    else{ 
     if(top->priority < pHead->priority){ 
      top = pHead; 
      pHead->prev = pos->prev; 
      pHead->next = pos; 
      pos->prev = pHead; 
     } 
     while(pHead->priority < pos->priority){ 
      pos = pos->next; 
      if(pos == null){ 
       pos->next = pHead; 
       pHead->prev = pos; 
       pHead->next = null; 
       return top; 
      } 
     } 
     (pos->prev)->next = pHead; 
     pHead->prev = pos->prev; 
     pHead->next = pos; 
     pos->prev = pHead; 

    } 
    return top; 
} 
void printNodes(){ 
    NODE * pos = head; 
    while(pos != null){ 
     printf("PRIORITY ORDER!:::::%d\n", pos->priority); 
     pos = pos->next; 
    } 
} 
int main(){ 

    nodes[0].priority = 10; 
    nodes[1].priority = 9; 
    nodes[2].priority = 8; 
    nodes[3].priority = 7; 
    nodes[4].priority = 6; 

    nodes[0].next = null; 
    nodes[1].next = null; 
    nodes[2].next = null; 
    nodes[3].next = null; 
    nodes[4].next = null; 

    nodes[0].prev = null; 
    nodes[1].prev = null; 
    nodes[2].prev = null; 
    nodes[3].prev = null; 
    nodes[4].prev = null; 

    head = function(&nodes[0], head); 
    printf("HEAD %p\n", head); 
    printf("PRIORITY ORDER!:::::%d\n", head->priority); 
    head = function(&nodes[1], head); 
    printf("PRIORITY ORDER!:::::%d\n", head->priority); 
    head = function(&nodes[2], head); 
    printf("PRIORITY ORDER!:::::%d\n", head->priority); 
    head = function(&nodes[3], head); 
    printf("PRIORITY ORDER!:::::%d\n", head->priority); 
    head = function(&nodes[4], head); 
    printf("PRIORITY ORDER!:::::%d\n", head->priority); 

    printNodes(); 

    return 0; 
}

輸出：

HEAD 0x600c20 
PRIORITY ORDER!:::::10 
Segmentation fault (core dumped)

來源

2014-10-10 syphjos

您是否嘗試過調試 – 2014-10-10 01:49:05

該程序似乎顯然不完整。你將所有'next'和'prev'指針設置爲'null'，然後嘗試使用它們。 – 2014-10-10 01:50:00

@GregHewgill我相信代碼試圖將'next'和'prev'鏈接到一個列表順序，根據'priority'中整數的順序排列順序 – 2014-10-10 02:03:49

該段錯誤的原因是：

if(pos == null){ 
    pos->next = pHead;

取消引用空指針。

由於變量名稱不一致，我無法跟蹤代碼（top是head和pHead是下一個節點等）。

來源

2014-10-10 01:54:32

謝謝，如果您無法辨別，我是個白癡 – syphjos 2014-10-10 02:39:11

C結構指針作爲參數：對結構進行永久更改

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