二进制搜索树和结构错误

Question

This program should create a binary search tree, insert numbers 1-366 into the tree and then should prompt the user to enter a number to see if the number is in the binary search tree. It worked when it was all in one C file but I now need to make it modular and have main in a separate file but it now gives me errors that I don't understand.

I've got 3 files:

map.h:

#include <stdbool.h>

typedef struct tree Tree;
typedef struct node Node;

//creates a new tree
Tree *new_tree();

//create a new node
Node* NewNode(int data);

//insert in to the binary tree
Node* insert(Node* node, int data);

//search for nodes to see if they exist
bool NodeSearch(Node* node,int data);

map.c:

//Binary search tree implementation
#include <stdio.h>
#include <stdlib.h>
#include "map.h"

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

//tree wrapper structure
struct tree {
    struct node *root;
} ;

//create a new tree
Tree *new_tree() {
    Tree *t = malloc(sizeof(Tree));
    t->root = NULL;
    return t;
}

//create a new node
Node* NewNode(int data) {
  Node* node = malloc(sizeof *node);    // "new" is like "malloc"
  node->data = data;
  node->left = NULL;
  node->right = NULL;

  return(node);
}

//insert in to the binary tree
Node* insert(Node* node, int data) {
  // 1. If the tree is empty, return a new, single node
  if (node == NULL) {
    return(NewNode(data));
  }
  else {
    // 2. Otherwise, recur down the tree
    if (data <= node->data) node->left = insert(node->left, data);
    else node->right = insert(node->right, data);

    return(node); // return the (unchanged) node pointer
  }
}
//search for nodes to see if they exist
bool NodeSearch(Node* node,int data) {
    if(node==NULL) return false;
    else if(node->data == data) return true;
    else if(data  <= node ->data) return NodeSearch(node->left, data);
    else return NodeSearch(node->right, data);
}

mainphone.c:

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

int main(){
    struct node* root = NULL;

    for (int i = 1; i < 367; i++) {
        root = insert(root,i);
        Node *n = NewNode (i);
        insert (n, n->data);}

    int number;
    printf("Enter Number\n");
    scanf("%d",&number);
    if(NodeSearch(root, number) == true) printf("Found\n");
    else printf("Not found\n");


}

the errors it gives me are:

mainphone.c:11:15: error: incomplete definition of type 'struct node'
            insert (n, n->data);}
                       ~^

./map.h:4:16: note: forward declaration of 'struct node'
typedef struct node Node;
           ^

mainphone.c:16:5: error: implicit declaration of function 'NodeSearch' is
  invalid in C99 [-Werror,-Wimplicit-function-declaration]
    if(NodeSearch(root, number) == true) printf("Found\n");

Answer 1

First error is because while main.c has the declaration of a struct node, the actual structure definition is in map.c, and mainphone.c does not know it.

Now this is usually a good thing, since it forces us to encapsulate. If you want to keep your structures in map.c, you'll need to create functions to access their data from outside.

The second error is most likely a compilation one. Be sure to either link a previously compiled map.o to mainphone.c:

gcc (FLAGS_HERE) map.c -c
gcc (FLAGS HERE) map.o mainphone.c -o (YOUR_EXECUTABLE_NAME)

or use the automagical *.c syntax.

gcc (FLAGS_HERE) *.c -o (YOUR_EXECUTABLE_NAME)