我是否因为出现了分裂错误 [英] Whya am I getting segementation fault

问题描述

请告诉我为什么我在此代码中出现分段错误。我在第72行遇到错误。我想通过linkA创建另一个节点链接，但我不能。当我第一次尝试访问节点时 - > linkA = temp我得到错误



我尝试过： < br $> b $ b

  typedef   struct  node 
 {
  char  word [ 100 ]; 
  char 含义[ 100 ]; 
  struct  node * link; 
} * wordptr; 
 
  typedef   struct  alphanode 
 {
  char 字[ 100 ]; 
  char 含义[ 100 ]; 
  struct  alphanode * linkA; 
 
  struct  alphanode * linkB; 
} *字母; 
 
 
  int  main（）
 {
  int  i =  1 ; 
首先是字母，temp; 
 
 alphabets tempfirst =（alphabets）malloc（ sizeof （ struct  alphanode）） ; 
 
 tempfirst-> linkA = NULL; 
 tempfirst-> linkB = NULL; 
 
 first = temp; 
 
 
  //  创建26个链接节点 
  for （i =  1 ; i< =  26 ; i ++）
 {
 temp =（alphabets）malloc（ sizeof （ struct  alphanode））; 
 tempfirst-> linkB = temp; 
 
 
 temp-> linkA = NULL; 
 temp-> linkB = NULL; 
 
 tempfirst = temp; 
} 
 
 
 enterAlpha（  bcd ，第一）; 
 displayMyDictionary（first）; 
 
 printf（  Hello world！\ n）; 
  return   0 ; 
} 
 
  void  enterAlpha（ char  str []，字母首先）
 {
  int  i =  0 ; 
 
  //  转到alphate起始节点 
 的类=code-keyword>（i =  0 ; i< =（（ int ）str [ 0 ]  -  '  a'）; i ++）
 {
 first = first-> linkB; 
} 
 
 alphabets temp =（字母）malloc（ sizeof （ struct  alphanode））; 
 first-> linkA = temp; 
 first = temp; 
 printf（ ％s，first-> word）; 
 
 
} 

解决方案

Quote：

first = temp;

应该是

 first = tempfirst; 

你的第一个指针无效，因为它是用不确定的值初始化的：

 / /这些都没有初始化，因此包含不确定的值
 //最好将它们设置为NULL并使用适当的检查
 //以后再使用它们
 alphabets first，temp; 
 
 alphabets tempfirst =（alphabets）malloc（sizeof（struct alphanode））; 
 
 tempfirst-> linkA = NULL; 
 tempfirst-> linkB = NULL; 
 
 //因为temp没有初始化，所以首先包含一个不确定的值
 first = temp; 
 
 // ... 
 
 //在这里传递无效指针
 enterAlpha（bcd，first）; 
 displayMyDictionary（first）; 

更好的代码会做这样的事情：

 #include< assert.h> 
 
 int main（）
 {
 alphabets first = NULL; 
 alphabets temp = NULL; 
 // ... ... 
} 
 
 void enterAlpha（char str []，首先是字母）
 {
 //打破调试版本
断言（str！= NULL）; 
断言（首先！= NULL）; 
 
 //使用发布版本避免seg错误
 if（NULL == first）
 return; 
 
 // ... 
} 

please tell me why am i getting segmentation fault in this code.I am getting an error at 72nd line. I wanted to make another node link though linkA but I can't. When ever I try to access the node by writing first->linkA=temp i get the error

What I have tried:

typedef struct node
        {
          char word[100];
          char meaning[100];
          struct node *link;
        }*wordptr;
        
        typedef struct alphanode
        {
        char word[100];
        char meaning[100];
        struct alphanode *linkA;
        
        struct alphanode *linkB;
        }*alphabets;
        
        
        int main()
        {
            int i=1;
            alphabets first, temp;
        
            alphabets tempfirst=(alphabets)malloc(sizeof(struct alphanode));
        
            tempfirst->linkA=NULL;
            tempfirst->linkB=NULL;
        
            first=temp;
        
        
            //creating 26 linked nodes
            for(i=1;i<=26;i++)
            {
              temp=(alphabets)malloc(sizeof(struct alphanode));
              tempfirst->linkB=temp;
        
        
              temp->linkA=NULL;
              temp->linkB=NULL;
        
              tempfirst=temp;
            }
        
        
            enterAlpha("bcd", first);
            displayMyDictionary(first);
        
            printf("Hello world!\n");
            return 0;
        }
        
        void enterAlpha(char str[], alphabets first)
        {
        int i=0;
        
           //takes to the alphate starting node
          for(i=0;i<=((int)str[0]-'a');i++)
          {
            first=first->linkB;
          }
            
          alphabets temp = (alphabets)malloc(sizeof(struct alphanode));         
           first->linkA=temp;
           first=temp;
            printf("%s", first->word);
           
        
        }

解决方案

Quote:

first=temp;

should be instead

first=tempfirst;

Your first pointer is invalid because it is initialised with an indeterminate value:

// These are not initialised and contain therefore indeterminate values
// It would be better to set them to NULL and use appropriate checks
//  when using them later
alphabets first, temp;
        
alphabets tempfirst=(alphabets)malloc(sizeof(struct alphanode));
        
tempfirst->linkA=NULL;
tempfirst->linkB=NULL;

// Because temp is not initialised, first contains an indeterminate value too        
first=temp;

// ...

// Passing invalid pointers here
enterAlpha("bcd", first);
displayMyDictionary(first);

Better code would do something like this:

#include <assert.h>

int main()
{
    alphabets first = NULL;
    alphabets temp = NULL;
    // ...
}

void enterAlpha(char str[], alphabets first)
{
    // Break with debug builds
    assert(str != NULL);
    assert(first != NULL);

    // Avoid seg faults with release builds
    if (NULL == first)
        return;

    // ...
}

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