c - 知识树中的段错误

Question

我正在用 c 语言实现一个可以从文件中读取的知识树。我的 newStr 函数出现段错误。我无法用这个问题测试我的其余代码。我对c没有太多经验。任何帮助将不胜感激。

我的.c文件 ＃包括 ＃包括 #include“动物.h” ＃包括 #include

/*returns a new node for the given value*/
struct Node * newNode (char *newValue) 
{
struct Node * tree;
tree = (struct Node*)malloc(sizeof(struct Node));
tree -> value = newStr(newValue);
return tree;
}


/* returns a new string with value passed as an argument*/
char * newStr (char * charBuffer)
{
int i;
int length = strlen(charBuffer);
char newStr;
if(charBuffer[0] == 'A' || charBuffer[0] == 'Q'){
    for(i=1; i<length; i++)
        newStr += charBuffer[i]; 
}
return (newStr + "\0");
}

/*Read from a File and create a tree*/
struct Node * readATree(FILE * f)
{
  char c;
  char buffer[100];
  struct Node * newTree;
  c = fgetc(f);
  if (c == 'A'){
     fgets(buffer, 100, f);
     newTree = newNode(buffer);
     newTree -> left = NULL;
     newTree -> right = NULL;
    }
  else{
     fgets(buffer, 100, f);
     newTree = newNode(newStr(buffer));
     newTree->left = readATree(f);
     newTree->right = (struct Node *) readAtree(f);
     }
  return newTree;

}

/*Write Tree to a File*/
void writeAFile(struct Node* tree, FILE * f)
{
    char buffer[100];
    strcpy(buffer, tree->value);
    if(tree != 0){
        if(tree->left == NULL && tree->right == NULL){
            fputc((char)"A", f);
            fputs(buffer,f);
        } else{
            fputc((char)"Q",f);
            fputs(buffer,f);
            writeAFile(tree->left, f);
            writeAFile(tree->right,f);
        }
    }
}

/*The play should start from here*/
int main (){
    struct Node* node;
    struct Node* root;
    char ans[100];
    char q[100];
    FILE * f;
    f = fopen("animal.txt", "r+");
    if(f != NULL)
        readATree(f);
    else{
        node = newNode("Does it meow?");
    node->right = NULL;
    node->right->right=NULL;
    node->left->left=NULL;
    node->left=newNode("Cat");
    root = node;
}
while(node->left != NULL && node->right != NULL){
    printf(node->value);
    scanf(ans);
    if(ans[0] == (char)"Y" || ans[0] == (char)"y")
        node = node->left;
    else if(ans[0] == (char)"N" || ans[0] == (char)"n")
        node = node->right;
    else
        printf("That is not a valid input.\n");
}
if(ans[0] == (char)"Y" || ans[0] == (char)"y")
    printf("I win!");
else if(ans[0] == (char)"N" || ans[0] == (char)"n"){
    printf("What is your animal");
    scanf(ans);
    printf("Please enter a yes or no question that is true about %s?\n", ans);
    scanf(q);
    node->right = newNode(q);
    node->right->left = newNode(ans);
    node->right->right = NULL;
}
writeAFile(root,f);
fclose(f);
return 0;
}

.h文件 #include

struct Node {
char *value;
struct Node * left;
struct Node * right;
};

struct Node * newNode (char *newValue) ;
char * newStr (char * charBuffer);
struct Node * readATree(FILE * f);
void writeAFile(struct Node* tree, FILE * f);

Answer 1

可能还有几个，但这里有一些错误的地方:

1. 您的 newStr 函数非常， 非常错误。我猜你会想要 像这样的东西:

   char * newStr (char * charBuffer)
   {
     char *newStr;
     if(charBuffer[0] == 'A' || charBuffer[0] == 'Q') {
       newStr = strdup(&charBuffer[1]);
     } else {
       newStr = strdup("");
     }
     if(newStr == NULL) {
         //handle error
     }
     return newStr;
   }
   

2. 您不能将字符串转换为字符 就像你在这里做的那样:

    if(ans[0] == (char)"Y" || ans[0] == (char)"y")
   

   改为执行(类似代码相同 别处也是)

    if(ans[0] =='Y' || ans[0] == 'y')
   

3. 调用putc时同上， 不要做

    fputc((char)"A", f);
   

   做

    fputc('A', f);
   

4. scanf 需要格式字符串，不需要 做:

   scanf(ans);
   

   例如(或者再次使用 fgets)

   if(scanf("%99s",ans) != 1) {
      //handle error
    }