#include <stdio.h>
#include <stdlib.h>
struct node{
  int data;
  struct node *next;
};
   struct node *top=NULL;   // global variable
int isempty()
{
     if( top == NULL)  // nothing is write because global variable will declare in first
     return 1;
     else
     return 0;
}
int isfull()   // nothing is write because global variable will declare in first
{    struct node *p=(struct node *)malloc(sizeof(struct node));
     if(p == NULL)  //  this indicate no space found in heap memeory
     return 1;
     else
     return 0;
}
struct node *push(int val)  // only value write because global variable will declare in first
{     if(isfull(top)){
      printf("stack over flow \n");
       }
    else{
   struct node * n=(struct node *)malloc(sizeof(struct node));
    n -> data = val;
    n -> next=  top;
   top = n;
    return top;
    }
}
int pop()   
{    if(isempty(top))
     {
          printf("stack under flow \n");
      }
      else{
        struct node *n= top;
       top =  top -> next;
        int x= n -> data;
        free(n);
        return x;
      }

}
int peek(int position)
{  struct node *ptr=top;
  for(int i=1;i<position ;i++)
  {
    ptr = ptr -> next;
  }
  
   return ptr -> data;
  
}
void linkedlist(struct node *ptr)
{
  while (ptr !=NULL)
  {
    printf("element are %d \n",ptr -> data);
    ptr = ptr -> next;
  }
  
}
int main()
{
    top=push(1);
    top=push(2);
    top=push(3);
    top=push(4);
    top=push(5);
   linkedlist(top);
    printf("%d element are popped \n",pop());   
    printf("%d element are popped \n",pop());
    printf("%d element are popped \n",pop());
    
    printf("peek element are %d \n",peek(2));
    printf("top of the element are %d \n",top -> data);
    
}

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
}