C语言程序设计 遍历二叉树

#include <stdio.h>
#include <stdlib.h>
typedef struct BiTNode
{
    int data;                        // 数据域保存数据
    struct BiTNode *lchild, *rchild; // 指针域分别指向左子树和右子树
} BiTNode, *BiTree;

bool InitBiTree(BiTree &btree, int e)
{
    btree = (BiTNode *)malloc(sizeof(BiTNode));
    btree->data = e;
    btree->lchild = NULL;
    btree->rchild = NULL;
    return true;
}

bool BiTreeInsert(BiTree &btree, int e, int location)
{
    BiTNode *nTree = NULL;
    InitBiTree(nTree, e);
    if (location == 1)
    {
        btree->lchild = nTree;
    }
    else if (location == 0)
    {
        btree->rchild = nTree;
    }
    return true;
}

int visitNode(BiTree btree)
{
    return btree->data;
}

void PreOrder(BiTree btree, int &sum)
{
    if (btree != NULL)
    {
        sum += visitNode(btree);
        PreOrder(btree->lchild, sum);
        PreOrder(btree->rchild, sum);
    }
}
int main()
{
    // 初始化树
    BiTree btree = NULL;
    InitBiTree(btree, -4);
    BiTreeInsert(btree, 5, 1);
    BiTreeInsert(btree, 10, 0);
    BiTreeInsert(btree->lchild, -3, 1);
    BiTreeInsert(btree->rchild, 20, 1);
    BiTreeInsert(btree->rchild, 7, 0);
    int sum = 0;
    PreOrder(btree, sum);
    printf("%d", sum);
    return 0;
}

运行结果如下：