c - C中的二叉树

我在C中创建二叉树时遇到了问题。我想我可以将图书添加到树中，在树中，将具有较后出版年份的图书添加到左边，将较早出版年份的图书添加到右边。我一直有跑步错误，我不知道为什么。

#include <stdio.h>
#include <stdlib.h>


struct book {
    char* name;
    int year;
};

typedef struct tnode {
    struct book *aBook;
    struct tnode *left;
    struct tnode *right;
} BTree;

BTree* addBook(BTree* nodeP, char* name, int year){
    if( nodeP == NULL )
    {
        nodeP = (struct tnode*) malloc( sizeof( struct tnode ) );
        (nodeP->aBook)->year = year;
        (nodeP->aBook)->name = name;
        /* initialize the children to null */
        (nodeP)->left = NULL;
        (nodeP)->right = NULL;
    }
    else if(year > (nodeP->aBook)->year)
    {
        addBook(&(nodeP)->left,name,year );
    }
    else if(year < (nodeP->aBook)->year)
    {
        addBook(&(nodeP)->right,name,year );
    }
    return nodeP;
}

void freeBTree(BTree* books)
{
    if( books != NULL )
    {
        freeBTree(books->left);
        freeBTree(books->right);
        //free( books );
    }
}

void printBooks(BTree* books){
    if(books != NULL){

    }
}

int main(int argc, char** argv) {
    BTree *head;
    head = addBook(head,"The C Programming Language", 1990);
    /*addBook(head,"JavaScript, The Good Parts",2008);
    addBook(head,"Accelerated C++: Practical Programming by Example", 2000);
    addBook(head,"Scala for the impatient",2012);*/
}

最佳答案

一个问题是您没有初始化为空：

BTree *head;

应该是

BTree *head = NULL;

我建议将编译器警告设置得更高。您的两个递归调用不正确，编译器应该对此发出警告：

addBook(&(nodeP)->left,name,year );

应该是：

addBook( nodeP->left,name,year );

从参数传递的角度来看。但是，此函数现在无法正常工作，因为在节点指针为空时添加，这意味着您不能将父节点附加到子节点，因为父指针节点已不存在。我认为逻辑应该检查适用的右/左节点，如果为空，则在例程中向右添加，否则递归调用，直到找到右/左指针为空的节点。
像这样的：

BTree *makeNode(char *name, int year)
{
   // NOTE: 3 frees required for every node
   BTree *nodeP = malloc( sizeof( struct tnode ) );  // 1
   nodeP->aBook = malloc( sizeof(struct book) );     // 2
   (nodeP->aBook)->year = year;
   (nodeP->aBook)->name = malloc(strlen(name) + 1);  // 3
   strcpy((nodeP->aBook)->name,name);
   /* initialize the children to null */
   nodeP->left = NULL;
   nodeP->right = NULL;
   return nodeP;
}

BTree* addBook(BTree* nodeP, char* name, int year)
{
    if ( nodeP == NULL )
    {
        nodeP = makeNode(name,year);
    }
    else if (year > (nodeP->aBook)->year)
    {
       if ( nodeP->left == NULL )
          nodeP->left = makeNode(name,year);
       else
          addBook( nodeP->left,name,year );
    }
    else if(year < (nodeP->aBook)->year)
    {
       if ( nodeP->right == NULL )
          nodeP->right = makeNode(name,year);
       else
          addBook( nodeP->right,name,year );
    }
    return nodeP;
}

void printBooks(BTree* books)
{
    if (books != NULL) {
       printf("book: %s %d\n",books->aBook->name,books->aBook->year);
       printBooks(books->right);
       printBooks(books->left);
    }
}

关于c - C中的二叉树，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/12574506/