C++ Data Structures - Linked List Other Related Topics
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C++ - Delete the first node of the Linked List



In this method, the first node of the linked list is deleted. For example - if the given list is 10->20->30->40 and the first node is deleted, the list becomes 20->30->40.

Deleting the first node of the Linked List is very easy. If the head is not null then create a temp node pointing to head and move head to the next of head. Then delete the temp node.

Linked List - Delete First Node

The function pop_front is created for this purpose. It is a 3-step process.

void pop_front() {
  if(head != NULL) {
    
    //1. if head is not null, create a
    //   temp node pointing to head
    Node* temp = head;

    //2. move head to next of head
    head = head->next; 

    //3. delete temp node
    free(temp); 
  }
}

The below is a complete program that uses above discussed concept of deleting the first node of the linked list.

#include <iostream>
using namespace std;

//node structure
struct Node {
    int data;
    Node* next;
};

class LinkedList {
  private:
    Node* head;
  public:
    LinkedList(){
      head = NULL;
    }
 
    //Add new element at the end of the list
    void push_back(int newElement) {
      Node* newNode = new Node();
      newNode->data = newElement;
      newNode->next = NULL; 
      if(head == NULL) {
        head = newNode;
      } else {
        Node* temp = head;
        while(temp->next != NULL)
          temp = temp->next;
        temp->next = newNode;
      }    
    }

    //Delete first node of the list
    void pop_front() {
      if(head != NULL) {
        Node* temp = head;
        head = head->next; 
        free(temp); 
      }
    }

    //display the content of the list
    void PrintList() {
      Node* temp = head;
      if(temp != NULL) {
        cout<<"The list contains: ";
        while(temp != NULL) {
          cout<<temp->data<<" ";
          temp = temp->next;
        }
        cout<<endl;
      } else {
        cout<<"The list is empty.\n";
      }
    }    
};

// test the code 
int main() {
  LinkedList MyList;

  //Add four elements in the list.
  MyList.push_back(10);
  MyList.push_back(20);
  MyList.push_back(30);
  MyList.push_back(40);
  MyList.PrintList();
  
  //Delete the first node
  MyList.pop_front();
  MyList.PrintList();  
  return 0; 
}

The above code will give the following output:

The list contains: 10 20 30 40
The list contains: 20 30 40  

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