我在 Turbo C++ 中使用 struct — 它给出的错误声明是不允许的

Question

Error in Turbo C++:

I compile this file in Turbo C++ but it takes many errors type of struct declaration is not allowed.

Here is the code:

#include<stdio.h>
#include<malloc.h>

struct node{
    int data;
    struct node* left;
    struct node* right;
};

struct node* createNode(int data){
    struct node *n; // creating a node pointer
    n = (struct node *) malloc(sizeof(struct node)); //
    n->data = data;
    n->left = NULL;
    n->right = NULL;
    return n;
}
void inOrder(struct  node* root){
    if(root!=NULL)
    {
        inOrder(root->left);
        printf("%d ", root->data);
        inOrder(root->right);
    }
}
struct node * search(struct node* root, int key){
    if(root==NULL)
    {
        return NULL;
    }
    if(key==root->data)
    {
        return root;
    }
    else if(key<root->data)
    {
        return search(root->left, key);
    }
    else{
        return search(root->right, key);
    }
}
void insert(struct node *root, int key){
    struct node *prev = NULL;
    while(root!=NULL){
        prev = root;
        if(key==root->data){
            printf("Cannot insert %d, already in BST", key);
            return;
        }
        else if(key<root->data){
            root = root->left;
        }
        else{
            root = root->right;
        }
    }
    struct node* new = createNode(key);
    if(key<prev->data){
        prev->left = new;
    }
    else{
        prev->right = new;
    }
}
struct node *inOrderPredecessor(struct node *root){
    root = root->left;
    while (root->right!=NULL)
    {
        root = root->right;
    }
    return root;
}
struct node *deleteNode(struct node *root, int value)
{
    struct node* iPre;
    if (root == NULL){
        return NULL;
    }
    if (root->left==NULL&&root->right==NULL)
    {
        free(root);
        return NULL;
    }
    if (value < root->data){
        root-> left = deleteNode(root->left,value);
    }
    else if (value > root->data){
        root-> right = deleteNode(root->right,value);
    }
    //deletion strategy when the node is found
    else{
        iPre = inOrderPredecessor(root);
        root->data = iPre->data;
        root->left = deleteNode(root->left, iPre->data);
    }
    return root;
}
int main(){
    struct node *p = createNode(8);
    insert(p,3);
    insert(p,1);
    insert(p,6);
    insert(p,7);
    insert(p,10);
    insert(p,14);
    insert(p,4);
    inOrder(p);
    printf("\n After Deleting NOde\n");
    deleteNode(p,4);
    inOrder(p);
    struct node* n = search(p, 6);
    if(n!=NULL){
        printf("\nFound Element : %d", n->data);
    }
    else{
        printf("Element not found");
    }
    return 0;
}

This code runs smoothly in VSCODE but I want to run in Turbo C++.

How can I fix it?

I am a beginner in data structures. A struct is a type consisting of a sequence of members whose storage is allocated in an ordered sequence (as opposed to union, which is a type consisting of a sequence of members whose storage overlaps)

Answer 1

Turbo C++ is extremely obsolete compiler. It supports very old C. It requires all variable declarations to be placed in the first lines after opening braces. For example

struct node* new = createNode(key);

Should be split

struct node* new = NULL;  // goes up to struct node* next = NULL;
...
new = createNode(key);  // initialization in a desired line

void insert(struct node *root, int key){
    struct node *prev = NULL;
    struct node* new = NULL; // <--
    while(root!=NULL){
        prev = root;
        if(key==root->data){
            printf("Cannot insert %d, already in BST", key);
            return;
        }
        else if(key<root->data){
            root = root->left;
        }
        else{
            root = root->right;
        }
    }
    new = createNode(key); // <--
    if(key<prev->data){
        prev->left = new;
    }
    else{
        prev->right = new;
    }
}

Split similarly all late declarations with initializations to early declarations and late initializations.