{if（！p）delete [] p;}

这是一个 C++ 语言中的代码片段，用于释放指针 p 所指向的动态分配内存空间。其中，if (!p) 表示判断指针 p 是否为空指针，如果为空指针则直接返回，不执行后续的操作；而 delete [] p 表示释放 p 所指向的数组型动态分配内存空间。需要注意的是，p 所指向的内存空间必须是通过 new [] 分配的，否则会导致未定义的行为。

相关问题

#include<iostream> using namespace std; typedef struct ElemType{ int key; }ElemType; typedef struct BSTNode{ ElemType data; BSTNode *lchild,*rchild; }BSTNode,*BSTree; int flag=1; void InsertBST(BSTree &T,ElemType e ) ;//实现细节隐藏 void CreateBST(BSTree &T ) ;//实现细节隐藏 void InOrderTraverse(BSTree &T)；//中序遍历，实现细节隐藏 void DeleteBST(BSTree &T,char key) { BSTree p=T;BSTree f=NULL; BSTree q; BSTree s; while(p){ if (p->data.key == key) break; f=p; if (p->data.key> key) p=p->lchild; else p=p->rchild; } if(!p) ; if ((p->lchild)&& (p->rchild)) { q = p; s = p->lchild; while (s->rchild) {q = s; s = s->rchild;} p->data= s->data; if(q!=p) ; else ; delete s; } else{ if(!p->rchild) { q = p; p = p->lchild; } else if(!p->lchild) { q = p; p = p->rchild; } if(!f) ; else if (q==f->lchild) ; else ; delete q; } } int main() { BSTree T; CreateBST(T); int key; cin>>key; DeleteBST(T,key); InOrderTraverse(T); }补全这个代码 使他能够运转

完整代码如下：

#include<iostream> 
using namespace std; 

typedef struct ElemType{
    int key; 
}ElemType; 

typedef struct BSTNode{
    ElemType data; 
    BSTNode *lchild,*rchild; 
}BSTNode,*BSTree; 

int flag=1; 

void InsertBST(BSTree &T,ElemType e ) {
    if(!T) {
        BSTree S = new BSTNode;
        S->data =e;
        S->lchild = S->rchild = NULL;
        T = S; 
    }
    else if (e.key< T->data.key)
        InsertBST(T->lchild, e); 
    else if (e.key> T->data.key)
        InsertBST(T->rchild, e); 
} 

void CreateBST(BSTree &T ) {
    int i=1,n;
    cin >> n;
    T=NULL;
    ElemType e;
    while(i<=n){
        cin>>e.key;
        InsertBST(T, e);
        i++;
    }
} 

void InOrderTraverse(BSTree &T) {
    if(T) {
        InOrderTraverse(T->lchild);
        if(flag){cout<<T->data.key;flag=0;}
        else cout<<" "<<T->data.key;
        InOrderTraverse(T->rchild);
    } 
} 

void DeleteBST(BSTree &T,char key) {
    BSTree p=T;
    BSTree f=NULL;
    BSTree q;
    BSTree s;
    while(p){
        if (p->data.key == key) break;
        f=p;
        if (p->data.key> key)  p=p->lchild;
        else p=p->rchild;
    } 
    if(!p)  cout<<"找不到此节点"<<endl;
    else if ((p->lchild)&& (p->rchild)) {
        q = p;
        s = p->lchild;
        while (s->rchild) {
            q = s; 
            s = s->rchild;
        }
        p->data= s->data;
        if(q!=p) q->rchild=s->lchild;
        else q->lchild=s->lchild;
        delete s; 
    } 
    else{
        if(!p->rchild) { q = p; p = p->lchild; }
        else if(!p->lchild) { q = p; p = p->rchild; }
        if(!f) T=p; 
        else if (q==f->lchild) f->lchild=p;
        else f->rchild=p;
        delete q;
    } 
} 

int main() {
    BSTree T;
    CreateBST(T);
    int key;
    cin>>key;
    DeleteBST(T,key);
    InOrderTraverse(T);
    return 0;
}

这份代码可以创建一棵二叉搜索树，并支持删除指定节点。其中，`CreateBST` 函数用于创建二叉搜索树，`InsertBST` 函数用于向二叉搜索树中插入节点，`InOrderTraverse` 函数用于中序遍历二叉搜索树并输出节点的值，`DeleteBST` 函数用于删除指定节点。

#include<stdio.h> #include<stdlib.h> typedef struct BiTNode { int key; struct BiTNode *lchild, *rchild; } BiTNode, *BiTree; int SearchBST(BiTree T, int key, BiTree f, BiTree &p) { if (!T) { p = f; return 0; } else if (key == T->key) { p = T; return 1; } else if (key < T->key) SearchBST(T->lchild, key, T, p); else SearchBST(T->rchild, key, T, p); } int InsertBST(BiTree &T, int key) { if (!T) { T = (BiTree)malloc(sizeof(BiTNode)); T->key = key; T->lchild = (T)->rchild = NULL; } if (key == T->key) return 0; if (key > T->key) InsertBST(T->rchild, key); else InsertBST(T->lchild, key); } void InorderTraverse(BiTree T) { if (T){ InorderTraverse(T->lchild); printf("%d ", T->key); InorderTraverse(T->rchild); } } void Delete(BiTree &p) { BiTree q, s; if (!p->lchild && !p->rchild) p = NULL; else if (!p->lchild) { q = p; p = p->rchild; free(q); } else if (!p->rchild) { q = p; p = p->lchild; free(q); } else{ q = p; s = p->lchild; while (s->rchild) { q = s; s = s->rchild; } p->key = s->key; if (q != p) q->rchild = s->lchild; else q->lchild = s->lchild; free(s); } } int DeleteBST(BiTree &T, int key) { if (!T) return 0; else{ if (key == T->key) Delete(T); else if (key < T->key) DeleteBST(T->lchild, key); else DeleteBST(T->rchild, key); } } int main() { int e, n; BiTree T = NULL, f = 0, p; printf("输入长度："); scanf("%d", &n); printf("输入元素："); while (n--){ scanf("%d", &e); InsertBST(T, e); } printf("中序遍历："); InorderTraverse(T); printf("\n"); while (1) { printf("输入要查找元素："); scanf("%d", &e); if (SearchBST(T, e, f, p)) printf("找到了\n"); else printf("没找到\n"); printf("输入要插入元素："); scanf("%d", &e); InsertBST(T, e); printf("中序遍历："); InorderTraverse(T); printf("\n"); printf("输入要删除元素："); scanf("%d", &e); DeleteBST(T, e); printf("中序遍历："); InorderTraverse(T); printf("\n"); } }请帮我注视本段代码

好的，以下是本段代码的注释：

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

//定义二叉搜索树的节点结构体 
typedef struct BiTNode  
{ 
    int key; //节点值 
    struct BiTNode *lchild, *rchild; //左右子节点 
} BiTNode, *BiTree; 

//在二叉搜索树T中查找值为key的节点，f为T的父节点，p为查找结果 
int SearchBST(BiTree T, int key, BiTree f, BiTree &p) 
{ 
    if (!T) 
    { 
        p = f; 
        return 0; //未找到 
    } 
    else if (key == T->key) 
    { 
        p = T; 
        return 1; //找到 
    } 
    else if (key < T->key) 
        SearchBST(T->lchild, key, T, p); 
    else 
        SearchBST(T->rchild, key, T, p); 
} 

//在二叉搜索树T中插入值为key的节点 
int InsertBST(BiTree &T, int key) 
{ 
    if (!T) 
    { 
        T = (BiTree)malloc(sizeof(BiTNode)); //申请新节点 
        T->key = key; 
        T->lchild = (T)->rchild = NULL; //左右子节点置为空 
    } 
    if (key == T->key) 
        return 0; //已有相同节点 
    if (key > T->key) 
        InsertBST(T->rchild, key); //插入右子树 
    else 
        InsertBST(T->lchild, key); //插入左子树 
} 

//中序遍历二叉搜索树 
void InorderTraverse(BiTree T) 
{ 
    if (T){ 
        InorderTraverse(T->lchild); 
        printf("%d ", T->key); 
        InorderTraverse(T->rchild); 
    } 
} 

//删除指定节点 
void Delete(BiTree &p) 
{ 
    BiTree q, s; 
    if (!p->lchild && !p->rchild) 
        p = NULL; 
    else if (!p->lchild) 
    { 
        q = p; 
        p = p->rchild; 
        free(q); 
    } 
    else if (!p->rchild) 
    { 
        q = p; 
        p = p->lchild; 
        free(q); 
    } 
    else
    { 
        q = p; 
        s = p->lchild; 
        while (s->rchild) 
        { 
            q = s; 
            s = s->rchild; 
        } 
        p->key = s->key; 
        if (q != p) 
            q->rchild = s->lchild; 
        else 
            q->lchild = s->lchild; 
        free(s); 
    } 
} 

//在二叉搜索树T中删除值为key的节点 
int DeleteBST(BiTree &T, int key) 
{ 
    if (!T) 
        return 0; //未找到 
    else
    { 
        if (key == T->key) 
            Delete(T); //找到并删除 
        else if (key < T->key) 
            DeleteBST(T->lchild, key); //在左子树中递归查找和删除 
        else 
            DeleteBST(T->rchild, key); //在右子树中递归查找和删除 
    } 
} 

//主函数 
int main() 
{ 
    int e, n; 
    BiTree T = NULL, f = 0, p; //T为二叉搜索树，f为T的父节点，p为查找结果 
    printf("输入长度："); 
    scanf("%d", &n); 
    printf("输入元素："); 
    while (n--)
    { 
        scanf("%d", &e); 
        InsertBST(T, e); //插入元素建树 
    } 
    printf("中序遍历："); 
    InorderTraverse(T); //中序遍历 
    printf("\n"); 
    while (1) 
    { 
        printf("输入要查找元素："); 
        scanf("%d", &e); 
        if (SearchBST(T, e, f, p)) 
            printf("找到了\n"); 
        else 
            printf("没找到\n"); 
        printf("输入要插入元素："); 
        scanf("%d", &e); 
        InsertBST(T, e); //插入元素 
        printf("中序遍历："); 
        InorderTraverse(T); //中序遍历 
        printf("\n"); 
        printf("输入要删除元素："); 
        scanf("%d", &e); 
        DeleteBST(T, e); //删除元素 
        printf("中序遍历："); 
        InorderTraverse(T); //中序遍历 
        printf("\n"); 
    } 
}