Stack_LL_Operations.c

#include<stdio.h>
#include<stdlib.h>


struct Node
{
    int data;
    struct Node *next;
};
struct Node *top=NULL;  // DACLARING TOP AS GLOBAL VARIABLE SO AS TO CHANGE IT IN THE MAIN FUNC

void linked_list_traversal(struct Node *ptr)
{
    while (ptr != NULL)
    {
        printf("Element : %d\n", ptr->data);
        ptr = ptr->next;
    }
}

int isEmpty(struct Node*top)
{
    if (top==NULL)
    {
        return 1;
    }
    else
    {
        return 0;
    }
    
}

int isFull(struct Node*top)
{
    struct Node *p=(struct Node*)malloc(sizeof(struct Node));
    if (p==NULL)
    {
        return 1;
    }
    else
    {
        return 0;
    }
    
}

struct Node* push(struct Node*top,int x)
{
    if (isFull(top))
    {
        printf("Stack Overflow\n");
    }
    else
    {
        struct Node *n=(struct Node*)malloc(sizeof(struct Node));
        n->data=x;
        n->next=top;
        top=n;
        return top;
    }
    
}

int pop(struct Node*tp)
{
    if (isEmpty(tp))
    {
        printf("Stack Underflow\n");
    }
    else
    {
        struct Node*n=tp;
        top=tp->next;
        int x=n->data;
        free(n);
        return x;
    }
    
}

int peek(int pos)
{
    struct Node *ptr=top;
    for (int i = 0; i < pos-1 && ptr!=NULL; i++)
    {
        ptr=ptr->next;
    }
    if (ptr!=NULL)
    {
        return ptr->data;
    }
    else
    {
        return -1;
    }
}

int main()
{
    
    int y,z;
    printf("Enter the element you want to push\n");
    scanf("%d",&y);
    printf("Enter the position you want to get the element\n");
    scanf("%d",&z);
    top=push(top,y);
    top=push(top,78);
    top=push(top,18);
    top=push(top,28);
    top=push(top,7);
    int ele=pop(top);
    printf("Popped element is %d\n",ele);
    linked_list_traversal(top);
    int seek_ele=peek(z);
    printf("Number at position %d is %d\n",z,seek_ele);
    for (int i = 1; i <=4; i++)
    {
        printf("Value at position %d is %d\n",i,peek(i));
    }
    
    return 0;
}