在P74里，郝斌老師，在結(jié)構(gòu)體創(chuàng)建時(shí)，沒(méi)有賦初值，而是在后面的Create...函數(shù)里賦的初值。

我嘗試在結(jié)構(gòu)里里面賦初值，而在后面函數(shù)里只建立部分連接，導(dǎo)致程序最后運(yùn)行到一半就卡住。

這是我的錯(cuò)誤源代碼：

#include <stdio.h>

#include <malloc.h>

struct BTNode {

struct BTNode* pLchild = NULL;

char BTData;

struct BTNode* pRchild = NULL;

};

struct BTNode* CreateTree();

void PreTraverse(BTNode* BTree);

void InTraverse(BTNode* BTree);

void PostTraverse(BTNode* BTree);

int main()

{

struct BTNode* BTHead = CreateTree();

printf("以下是先序遍歷的結(jié)果：\n");

PreTraverse(BTHead);

printf("\n");

printf("以下是中序遍歷的結(jié)果：\n");

InTraverse(BTHead);

printf("\n");

printf("以下是后序遍歷的結(jié)果：\n");

PostTraverse(BTHead);

}

//創(chuàng)建鏈?zhǔn)綐?/p>

struct BTNode* CreateTree()

{

struct BTNode* NodeA = (struct BTNode*)malloc(sizeof(BTNode));

struct BTNode* NodeB = (struct BTNode*)malloc(sizeof(BTNode));

struct BTNode* NodeC = (struct BTNode*)malloc(sizeof(BTNode));

struct BTNode* NodeD = (struct BTNode*)malloc(sizeof(BTNode));

struct BTNode* NodeE = (struct BTNode*)malloc(sizeof(BTNode));

NodeA->BTData = 'A';

NodeB->BTData = 'B';

NodeC->BTData = 'C';

NodeD->BTData = 'D';

NodeE->BTData = 'E';

NodeA->pLchild = NodeB;

NodeA->pRchild = NodeC;

NodeC->pLchild = NodeD;

NodeD->pRchild = NodeE;

return NodeA;

}

//遍歷鏈?zhǔn)綐?/p>

//1.先序遍歷

void PreTraverse(BTNode* BTree)

{

if (BTree == NULL)

{

return;

}

printf("%c ", BTree->BTData);

PreTraverse(BTree->pLchild);

PreTraverse(BTree->pRchild);

}

//2.中序遍歷

void InTraverse(BTNode* BTree)

{

if (BTree == NULL)

{

return;

}

PreTraverse(BTree->pLchild);

printf("%c ", BTree->BTData);

PreTraverse(BTree->pRchild);

}

//3.后序遍歷

void PostTraverse(BTNode* BTree)

{

if (BTree == NULL)

{

return;

}

PreTraverse(BTree->pLchild);

PreTraverse(BTree->pRchild);

printf("%c ", BTree->BTData);

}

在上網(wǎng)搜索原因后，才得知，C語(yǔ)言結(jié)構(gòu)體里不能賦初始值！

不知道為什么的，看參考鏈接：https://blog.csdn.net/Dontla/article/details/117920832

修改后的正確代碼：

【與上面的錯(cuò)誤代碼相比，這里的代碼只是將結(jié)構(gòu)體里的賦初值那部分去掉，然后在Create...函數(shù)里手動(dòng)為有空孩子的節(jié)點(diǎn)賦值為NULL】

#include <stdio.h>

#include <malloc.h>

struct BTNode {

/*正確寫法*/

struct BTNode* pLchild;

char BTData;

struct BTNode* pRchild;

};

struct BTNode* CreateTree();

void PreTraverse(BTNode* BTree);

void InTraverse(BTNode* BTree);

void PostTraverse(BTNode* BTree);

int main()

{

struct BTNode* BTHead = CreateTree();

printf("以下是先序遍歷的結(jié)果：\n");

PreTraverse(BTHead);

printf("\n");

printf("以下是中序遍歷的結(jié)果：\n");

InTraverse(BTHead);

printf("\n");

printf("以下是后序遍歷的結(jié)果：\n");

PostTraverse(BTHead);

}

//創(chuàng)建鏈?zhǔn)綐?/p>

struct BTNode* CreateTree()

{

struct BTNode* NodeA = (struct BTNode*)malloc(sizeof(BTNode));

struct BTNode* NodeB = (struct BTNode*)malloc(sizeof(BTNode));

struct BTNode* NodeC = (struct BTNode*)malloc(sizeof(BTNode));

struct BTNode* NodeD = (struct BTNode*)malloc(sizeof(BTNode));

struct BTNode* NodeE = (struct BTNode*)malloc(sizeof(BTNode));

NodeA->BTData = 'A';

NodeB->BTData = 'B';

NodeC->BTData = 'C';

NodeD->BTData = 'D';

NodeE->BTData = 'E';

NodeA->pLchild = NodeB;

NodeA->pRchild = NodeC;

NodeB->pLchild = NULL;

NodeB->pRchild = NULL;

NodeC->pLchild = NodeD;

NodeC->pRchild = NULL;

NodeD->pLchild = NULL;

NodeD->pRchild = NodeE;

NodeE->pLchild = NULL;

NodeE->pRchild = NULL;

return NodeA;

}

//遍歷鏈?zhǔn)綐?/p>

//1.先序遍歷

void PreTraverse(BTNode* BTree)

{

if (BTree == NULL)

{

return;

}

printf("%c ", BTree->BTData);

PreTraverse(BTree->pLchild);

PreTraverse(BTree->pRchild);

}

//2.中序遍歷

void InTraverse(BTNode* BTree)

{

if (BTree == NULL)

{

return;

}

PreTraverse(BTree->pLchild);

printf("%c ", BTree->BTData);

PreTraverse(BTree->pRchild);

}

//3.后序遍歷

void PostTraverse(BTNode* BTree)

{

if (BTree == NULL)

{

return;

}

PreTraverse(BTree->pLchild);

PreTraverse(BTree->pRchild);

printf("%c ", BTree->BTData);

}