c - 为什么会出现这个段错误？

Question

Program received signal SIGSEGV, Segmentation fault.
0x08048637 in insertWordDictR (string=0xbf87e7b6 "a", child=0x20f88,
    isTerminal=0x20f8c) at dictionary.c:54
54                        *isTerminal = False;

在我的头文件中

typedef enum {False, True} bool;

相关代码行如下:

dictLink insertWordDictR(char *string, dictLink child, bool* isTerminal){
  dictLink newWord;

  if(isTerminal != NULL){
    if(string[0] == '\0'){
          *isTerminal = True;
          return NULL;
    }else{
          *isTerminal = False;
    }
  }


  if (child == NULL){
      newWord = malloc(sizeof (struct dictEdge));
      newWord->thisChar = string[0];
      newWord->child = insertWordDictR(string + 1, newWord, &(newWord->isTerminal));             
      newWord->sibling = NULL;
  }else{
      newWord = insertIntoSiblingList(string, child);    

  }

  return newWord;
}

这一行是我如何调用这个函数的例子

  newWord->child = insertWordDictR(string + 1, newWord, &(newWord->isTerminal)); 

All files can be found here ，还有一个名为“testing”的输入文件。

Answer 1

在此序列中，您从未初始化的指针中获取字段的地址，如插入的注释所示:

dictLink result;
if(sibling == NULL){
      result = malloc(sizeof (struct dictEdge));
      result->thisChar = string[0];
      result->sibling = NULL;
      result->child = insertWordDictR(string + 1, result, &(result->isTerminal)); 

}else if(string[0] < sibling->thisChar){
      result = malloc(sizeof (struct dictEdge));
      result->thisChar = string[0];
      result->sibling = sibling;
      result->child = insertWordDictR(string + 1, result, &(result->isTerminal));  

  }else if(string[0] == sibling->thisChar){
      /* "result" has not been initialized, &(result->isTerminal) is an invalid pointer */
      sibling->child = insertWordDictR(string + 1, result, &(result->isTerminal)); 
    result = sibling;