Linked list intro program

Author: TonyStark-19

Linked-list/Linked-list-intro.cpp

@@ -14,7 +14,7 @@ class Node // class to create a node
     }
 };
 
-class List
+class List // class to add, delete, print and search nodes
 {
     Node *head;
     Node *tail;
@@ -25,7 +25,7 @@ class List
         head = tail = NULL;
     }
 
-    void push_front(int val)
+    void push_front(int val) // add node on front of linked list
     {
         Node *newNode = new Node(val);
 
@@ -41,28 +41,132 @@ class List
         }
     }
 
-    void printLL()
+    void push_back(int val) // add node on back or end of linked list
+    {
+        Node *newNode = new Node(val);
+
+        if (head == NULL) // empty linked list
+        {
+            head = tail = newNode;
+            return;
+        }
+        else // not empty
+        {
+            tail->next = newNode;
+            tail = newNode;
+        }
+    }
+
+    void pop_front() // delete node from front of linked list
+    {
+        if (head == NULL) // empty linked list
+        {
+            cout << "LL is empty\n";
+            return;
+        }
+
+        Node *temp = head;
+        head = head->next;
+        temp->next = NULL;
+
+        delete temp;
+    }
+
+    void pop_back() // delete node from back or end of linked list
+    {
+        if (head == NULL) // empty linked list
+        {
+            cout << "LL is empty\n";
+            return;
+        }
+
+        Node *temp = head;
+        while (temp->next != tail)
+        {
+            temp = temp->next;
+        }
+
+        temp->next = NULL;
+        delete tail;
+        tail = temp;
+    }
+
+    void insert(int val, int pos) // to insert or add a node at specific position
+    {
+        if (pos < 0)
+        {
+            cout << "Invalid position\n";
+            return;
+        }
+
+        if (pos == 0)
+        {
+            push_front(val);
+            return;
+        }
+
+        Node *temp = head;
+        for (int i = 0; i < pos - 1; i++)
+        {
+            if (temp == NULL)
+            {
+                cout << "Invalid position\n";
+                return;
+            }
+
+            temp = temp->next;
+        }
+
+        Node *newNode = new Node(val);
+        newNode->next = temp->next;
+        temp->next = newNode;
+    }
+
+    void printLL() // to print linked list
     {
         Node *temp = head;
 
         while (temp != NULL)
         {
-            cout << temp->data << "->";
+            cout << temp->data << " -> ";
             temp = temp->next;
         }
         cout << "NULL" << endl;
     }
+
+    int search(int key) // to search a node
+    {
+        Node *temp = head;
+        int idx = 0;
+
+        while (temp != NULL)
+        {
+            if (temp->data == key)
+            {
+                return idx;
+            }
+
+            temp = temp->next;
+            idx++;
+        }
+
+        return -1;
+    }
 };
 
 int main()
 {
     List ll;
 
-    ll.push_front(1);
-    ll.push_front(2);
     ll.push_front(3);
+    ll.push_front(2);
+    ll.push_front(1);
+
+    ll.insert(4, 1);
 
     ll.printLL();
 
+    cout << ll.search(2) << endl;
+
     return 0;
 }