我有一个 uni 任务,我必须在其中实现一个二叉搜索树。它必须获取信息并将其写入磁盘,并在树中保存一个索引。但是,每当我调用与树有关的函数时,程序就会崩溃。以下代码片段是我的 bTree.h 文件,以及导致崩溃的代码。
/* binary tree ADT */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define DATA_LENGTH 12
#define POS_LENGTH 8
struct INFO
{
char data[DATA_LENGTH];
int filePos;
};
struct NODE
{
struct INFO data;
struct NODE *left;
struct NODE *right;
};
/*
format for index data file
data identifier 12 bytes
position in file 8 bytes
--end of record-- total 20 bytes
*/
/*
Given a binary tree, return true if a node
with the target data is found in the tree. Recurs
down the tree, chooses the left or right
branch by comparing the target to each node.
*/
int lookupPos(struct NODE *node, char target[])
{
int length = strlen(target);
// 1. Base case == empty tree
// in that case, the target is not found so return false
if (node == NULL)
{
return -1;
}
else
{
// 2. see if found here, in which case return file pos.
if (strncmp(target, node->data.data, length) == 0)
{
return node->data.filePos;
}
else
{
// 3. otherwise recur down the correct subtree
if (strncmp(target, node->data.data, length) < 0)
{
return lookupPos(node->left, target);
}
else
{
return lookupPos(node->right, target);
}
}
}
}
/*
Give a binary search tree and a number, inserts a new node
with the given number in the correct place in the tree.
Returns the new root pointer which the caller should
then use (the standard trick to avoid using reference
parameters).
*/
struct NODE *insert(struct NODE *node, char info[], int pos)
{
int length = strlen(info);
// 1. If the tree is empty, return a new, single node
if (node == NULL)
{
struct INFO stuff;
strncpy(stuff.data, info, DATA_LENGTH);
stuff.filePos = pos;
node->data = stuff;
node->left = NULL;
node->right = NULL;
return(node);
}
else
{
// 2. Otherwise, recur down the tree
if (strncmp(info, node->data.data, length) <= 0)
{
node->left = insert(node->left, info, pos);
}
else
{
node->right = insert(node->right, info, pos);
}
return(node); // return the (unchanged) node pointer
}
}
struct NODE *loadTree(char filename[]) //cIndex.dat for customers, pIndex.dat for products
{
struct NODE *node;
char data[DATA_LENGTH];
char posStr[POS_LENGTH];
FILE* file;
file = fopen(filename,"rb");
char c;
fseek(file, 0, SEEK_SET);
while((c = fgetc(file)) != EOF) //reads until EOF char
{
fseek(file, -1, SEEK_CUR);
fread(data, sizeof(char), DATA_LENGTH, file);
fread(posStr, sizeof(char), POS_LENGTH, file);
insert(node, data, atoi(posStr));
}
fclose(file);
return node;
}
int saveTree(struct NODE *node, char filename[], int posInFile)
{
FILE *file;
file = fopen(filename, "r+b");
char c;
char posStr[POS_LENGTH];
fseek(file, posInFile, SEEK_SET);
while((c = fgetc(file)) != EOF)
{
fseek(file, -1, SEEK_CUR);
fwrite(node->data.data, sizeof(char), DATA_LENGTH, file);
sprintf(posStr, "%d", node->data.filePos);
fwrite(posStr, sizeof(char), POS_LENGTH, file);
posInFile = ftell(file);
saveTree(node->left, filename, posInFile);
saveTree(node->right, filename, posInFile);
}
fclose(file);
return 1;
}
int getSize(struct NODE *node)
{
if (node==NULL)
{
return 0;
}
else
{
return( getSize(node->left) + 1 + getSize(node->right));
}
}
现在有问题的代码片段:
int filePos = getSize(tree);
和
insert(tree, cust.id, filePos);
saveTree(tree, "cIndex.dat", 0);
谁能帮我?