 #include <iostream>
using namespace std;
class node{
  public:
  int data;
  node* prev;
  node* next;
  node(int n)
  {
    data=n;
    prev=nullptr;
    next=nullptr;
  }
  
};
void insertHead(node* &head,int data)
{
  node* n=new node(data);
  if(head ==nullptr)
  {
    head=n;
    return;
  }
  n->next=head;
  head->prev=n;
  head=n;
}
void insertTail(node* &head ,int data)
{
  node* n=new node(data);
  if(head ==nullptr)
  {
    head=n;
    return;
  }
  node* t=head;
  while(t->next!=nullptr)
  t=t->next;
  t->next=n;
  n->prev=t;
  
}
void delet(node* &head,int pos)
{ pos+=1;
  node* n=head;
  if(pos==1)
  {
    
    head=head->next;
    head->prev=nullptr;
    delete n;
    return ;
  }
  
  while(--pos)
  n=n->next;
  
  if(n->next!=nullptr)
  {
   n->next->prev=n->prev;
  }
  n->prev->next=n->next;
  delete n;
  
}
void print(node* head)
{ 
  std::cout << "NULL <=> ";
  while(head!=nullptr)
  {
    std::cout << head->data<<" <=> ";
    head=head->next;
  }
  std::cout << "NULL" << std::endl;
}


int main() 
{   int n;
    cin>>n;
    node* head=NULL;
    for (int i = 0; i < n; i++) {
      /* code */
      int c;
      cin>>c;
      insertTail(head,c);
      
    }
    print(head);
    cin>>n;
    for (int i = 0; i < n; i++) {
      /* code */
      int c;
      cin>>c;
      insertHead(head,c);
      
    }
    print(head);
    int pos;
    cin>>pos;
    delet(head,pos);
    print(head);
    
}

created 3 years ago by Ayu S

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

Supports different platforms like Windows, various Linux flavours, MacOS etc
C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
Case-sensitive
C++ is a compiler based language
C++ supports structured programming language
C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}