二叉树插入，帮我看valgrinds资料

Question

在一些基本的二叉树插入实现之后，我得到了一个内存错误。如果您能告诉我未来的学习过程，我将非常感激，在哪里可以找到 valgrind 的问题。我正在使用我在其他线程中阅读的内容或通过在线研究-v 或--leak-check=full 以及--show-leak-kinds=all 来查找有关内存泄漏的更多信息。

这是我的代码：

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


typedef int bool;
#define true 1
#define false 0

typedef struct _bstNode
{
    int data;
    struct _bstNode *left;
    struct _bstNode *right;
} bstNode;

bstNode *getNewNode(int number)
{
    bstNode *newNode = malloc(sizeof(bstNode));
    newNode->data = number;
    newNode->left = NULL;
    newNode->right = NULL;

    return newNode;
}

bstNode *insert(bstNode *root, int number)
{
    if(root == NULL)
    {
        root = getNewNode(number);
    }else if(root->data <= number)
    {
        root->left = insert(root, number);
    }else if(root->data > number)
    {
        root->right = insert(root, number);
    }else
    {
        printf("Error inserting number.\n");
    }
    return root;
}

/*bool search(bstNode *root, int toSearch)
{
    if(root == NULL)
    {
        return false;
    }
    if(root->data == toSearch)
    {
        return true;
    } else if(root->data <= toSearch)
    {
        return search(root->left, toSearch);
    } else if(root->data > toSearch)
    {
        return search(root->right, toSearch);
    }else
    {
        printf("Error searching for number\n");
        return false;
    }
}*/

void destroy_tree(bstNode *n)
{
    if(n->left)
    {
        destroy_tree(n->left);
    }
    if(n->right)
    {
        destroy_tree(n->right);
    }
    free(n);
}

int main()
{
    bstNode *root = NULL;

    root = insert(root, 8);
    root = insert(root, 12);
    root = insert(root, 43);
    root = insert(root, 22);
    root = insert(root, 2);
    root = insert(root, 8);

    /*if(search(root, 9) == true)
    {
        printf("Found\n");
    }else
    {
        printf("Number not found\n");
    }

    if(search(root, 22) == true)
    {
        printf("Found\n");
    }else
    {
        printf("Number not found\n");
    }*/

    destroy_tree(root);
    return 0;
}

==3990== Memcheck, a memory error detector
==3990== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==3990== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==3990== Command: ./test
==3990== 
==3990== Stack overflow in thread #1: can't grow stack to 0xffe801000
==3990== 
==3990== Process terminating with default action of signal 11 (SIGSEGV)
==3990==  Access not within mapped region at address 0xFFE801FF8
==3990== Stack overflow in thread #1: can't grow stack to 0xffe801000
==3990==    at 0x400633: insert (in /home/richie/Dokumente/learningc/test)
==3990==  If you believe this happened as a result of a stack
==3990==  overflow in your program's main thread (unlikely but
==3990==  possible), you can try to increase the size of the
==3990==  main thread stack using the --main-stacksize= flag.
==3990==  The main thread stack size used in this run was 8388608.
==3990== Stack overflow in thread #1: can't grow stack to 0xffe801000
==3990== 
==3990== Process terminating with default action of signal 11 (SIGSEGV)
==3990==  Access not within mapped region at address 0xFFE801FF0
==3990== Stack overflow in thread #1: can't grow stack to 0xffe801000
==3990==    at 0x4A28680: _vgnU_freeres (in /usr/lib/valgrind/vgpreload_core-amd64-linux.so)
==3990==  If you believe this happened as a result of a stack
==3990==  overflow in your program's main thread (unlikely but
==3990==  possible), you can try to increase the size of the
==3990==  main thread stack using the --main-stacksize= flag.
==3990==  The main thread stack size used in this run was 8388608.
==3990== 
==3990== HEAP SUMMARY:
==3990==     in use at exit: 24 bytes in 1 blocks
==3990==   total heap usage: 1 allocs, 0 frees, 24 bytes allocated
==3990== 
==3990== 24 bytes in 1 blocks are still reachable in loss record 1 of 1
==3990==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3990==    by 0x4005CA: getNewNode (in /home/richie/Dokumente/learningc/test)
==3990==    by 0x400615: insert (in /home/richie/Dokumente/learningc/test)
==3990==    by 0x4006F3: main (in /home/richie/Dokumente/learningc/test)
==3990== 
==3990== LEAK SUMMARY:
==3990==    definitely lost: 0 bytes in 0 blocks
==3990==    indirectly lost: 0 bytes in 0 blocks
==3990==      possibly lost: 0 bytes in 0 blocks
==3990==    still reachable: 24 bytes in 1 blocks
==3990==         suppressed: 0 bytes in 0 blocks
==3990== 
==3990== For counts of detected and suppressed errors, rerun with: -v
==3990== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Speicherzugriffsfehler (Speicherabzug geschrieben)

Answer 1

声明

    root->left = insert(root, number);

和

    root->right = insert(root, number);

导致无限递归，因为您不更改传递的根。相反，使用：

    root->left = insert(root->left, number);

和

    root->right = insert(root->right, number);

---

注意：您的if(root->data <= number) 可以创建一个副本。相反，请使用<，然后您的Error 分支会识别出重复项（这可能是也可能不是错误）。

Answer 2

在 valgrind 中哪里可以找到问题。

代码进行递归调用（insert() 调用自身而不是 returning）导致

==3990== Stack overflow in thread #1: can't grow stack to 0xffe801000

堆栈溢出意味着所有堆栈空间都在使用中。并且由于进程的堆栈空间是有限的，这种情况无法通过引发信号来解决该进程

==3990== Process terminating with default action of signal 11 (SIGSEGV)

要解决此问题，请将代码迟早从 insert() 调整为 return。

要了解堆栈溢出发生的位置，请使用符号编译（选项 -g 用于 GCC）并在调试器中运行代码，例如 gdb。

Answer 3

递归插入函数中的小错误

bstNode *insert(bstNode *root, int number)
{
    if(root == NULL)
    {
        root = getNewNode(number);
    }else if(root->data <= number)
    {
        root->left = insert(root->left, number);      // insert(root->left
    }else if(root->data > number)
    {
        root->right = insert(root->right, number);    // insert(root->right
    }else
    {
        printf("Error inserting number.\n");
    }
    return root;
}

如果root 不为 NULL，则应向下移动到右侧或左侧子树，直到找到 NULL 点来创建新节点。您原来的insert() 只是不断尝试插入root。