#include<stdio.h>
#include<stdlib.h>
struct node
{
    int data;
    struct node *next;
    struct node *prev;
}*head,*tail;
void create()
{
    int i,n;
    struct node *temp;
    printf("Enter the number of nodes:");
    scanf("%d",&n);
    head=(struct node *)malloc(sizeof(struct node));
    printf("Enter the data for 1st node:");
    scanf("%d",&head->data);
    head->prev=NULL;
    head->next=NULL;
    temp=head;
    for(i=2;i<=n;i++)
    {
        tail=(struct node *)malloc(sizeof(struct node));
        printf("Enter the data for %dth node:",i);
        scanf("%d",&tail->data);
        tail->prev=temp;
        tail->next=NULL;
        temp->next=tail;
        temp=tail;
    }
}
void display()
{
    struct node *temp=head;
    if(head==NULL)
    {
        printf("List is empty\n");
        return;
    }
    while(temp!=NULL)
    {
        printf("%d ",temp->data);
        temp=temp->next;
    }
}
void insert_beg()
{
    struct node *newnode=(struct node *)malloc(sizeof(struct node));
    printf("Enter the data for newnode:");
    scanf("%d",&newnode->data);
    newnode->prev=NULL;
    newnode->next=head;
    head->prev=newnode;
    head=newnode;
}
void insert_end()
{
    struct node *newnode=(struct node *)malloc(sizeof(struct node));
    printf("Enter the data for newnode:");
    scanf("%d",&newnode->data);
    newnode->next=NULL;
    newnode->prev=tail;
    tail->next=newnode;
    tail=newnode;
}
void insert_pos()
{
   int pos,i=1,n;
   struct node *newnode,*temp=head,*temp1=head;;
   printf("Enter the position to insert:");
   scanf("%d",&pos);
   while(temp!=NULL)
   {
       temp=temp->next;
       n++;
   }
   if(pos>n)
   {
       printf("Invalid position\n");
       return;
   }
   else
   {
       while(i<pos-1)
       {
           temp1=temp1->next;
           i++;
       }
       newnode=(struct node *)malloc(sizeof(struct node));
       printf("Enter the data for newnode:");
       scanf("%d",&newnode->data);
       newnode->prev=temp1;
       newnode->next=temp1->next;
       temp1->next=newnode;
       newnode->next->prev=newnode; 
   }
}
void delete_beg()
{
   struct node *temp=head; 
   if(head==NULL)
   {
       printf("List is empty\n");
       return; 
   }
   else
   {
      head=head->next; 
      head->prev=NULL; 
      free(temp); 
      return; 
   } 
}
void delete_end()
{
   struct node *temp=tail; 
   if(head==NULL)
   {
       printf("List is empty\n");
       return; 
   }
   else
   {
      tail=tail->prev; 
      tail->next=NULL; 
      free(temp); 
      return; 
   } 
}
void delete_pos()
{
  int pos,i=1,n;  
  struct node *temp=head,*temp1=head;  
  if(head==NULL)  
  {  
      printf("List is empty\n");  
      return;  
  }  
  else  
  {  
     printf("Enter the position to delete:");  
     scanf("%d",&pos);  
     while(temp!=NULL)  
     {  
         temp=temp->next;  
         n++;  
     }  
     if(pos>n)  
     {  
         printf("Invalid position\n");  
         return;  
     }  
     else if(pos==1)  
     {  
         delete_beg();  
     }  
     else if(pos==n)  
     {  
         delete_end();  
     }   
     else   
     {   
         while(i<pos-1)   
         {   
             temp1=temp1->next;   
             i++;   
         }

C Language online compiler

Write, Run & Share C Language code online using OneCompiler's C online compiler for free. It's one of the robust, feature-rich online compilers for C language, running the latest C version which is C18. Getting started with the OneCompiler's C editor is really 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 editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample C program which takes name as input and print your name with hello.

#include <stdio.h>
int main()
{
    char name[50];
    printf("Enter name:");
    scanf("%s", name);
    printf("Hello %s \n" , name );
    return 0;
    
}

About C

C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.

Key features:

  • Structured Programming
  • Popular system programming language
  • UNIX, MySQL and Oracle are completely written in C.
  • Supports variety of platforms
  • Efficient and also handle low-level activities.
  • As fast as assembly language and hence used as system development language.

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);

Arrays

Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.

Syntax

One dimentional Array:

data-type array-name[size];

Two dimensional array:

data-type array-name[size][size];

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.

Two types of functions are present in C

  1. Library Functions:

Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,

  1. User defined functions:

User defined functions are the ones which are written by the programmer based on the requirement.

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
}