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POpointer vs double pointer for Linked List and Binary Tree
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2013-08-23T07:57:10.827
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2016-10-14T21:00:50.733
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<ol> <li>For single linklist 1.1. This is what I saw from a tutorial, I only wrote the important part. <pre><code>sortedInsert(Node **root, int key){}; int main(){ Node *root = &a; sortedInsert(&root, 4); } </code></pre> 1.2. However I just used pointer rather than double pointer, and everything works fine, I can insert the key successfully. <pre><code>sortedInsert(Node *root, int key){}; int main(){ Node *root = &a; sortedInsert(root, 4); } </code></pre></li> <li>For binary Tree</li> </ol> 2.1. From tutorial(double pointer) <pre><code> void insert_Tree(Tree **root, int key){ } int main(){ Tree *root = NULL; insert_Tree(&root, 10); } </code></pre> 2.2. what I did is below, and I failed to insert the key, when I checked the node after insertion, the node is still null.(single pointer) <pre><code> void insert_Tree(Tree *root, int key){ if(root == NULL){ root = (Tree *)malloc(sizeof(Tree)); root->val = key; root->left = NULL; root->right = NULL; cout<<"insert data "<<key<<endl; }else if(key< root->val){ insert_Tree(root->left, key); cout<<"go left"<<endl; }else{ insert_Tree(root->right, key); cout<<"go right"<<endl; } } int main(){ Tree *root = NULL; insert_Tree(root, 10); } </code></pre> I have a few questions 1). which is right, 1.1/2.1 double pointer or 1.2/2.2 single pointer? Please explain in detail, it could be better if you can show an example, I think both of them are right. 2). Why did I insert key successfully in the linkedlist with single pointer, however I failed in the tree insertion with single pointer? Thanks very much, I appreciate everyone's help.
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<pointers><linked-list><binary-tree><insertion><double-pointer>
Title
pointer vs double pointer for Linked List and Binary Tree
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