stack-using-linkedlist

/* head is first node that is null initially, it'll be first node and it'll point to null, 
after adding second node, second node will point to first node and it'll be new head  now. 
it's diffrent than usaual where we tend to start with first node and first will point to 
second and last node will point to  null.*/



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


struct Node{                //created structure named as node
    int data;               //for storing data
    struct Node* next;      //for pointing to next noded
}*head;                     //pointer head for the node


void push(int data){
    struct Node *temp = (struct Node*)malloc(sizeof(struct Node));
    temp->data = data;
    if(head==NULL){ 
        temp -> next = NULL;  
        head = temp; 
    }
    else{
        temp->next = head;
        head = temp;
    }
    printf("Element pushed");
}
void pop(){
    if(head==NULL){
        printf("\nStack is empty");
    }
    else{
        printf("\nPopped element is %d",head->data);
        head = head->next;
    }
}
void peep(){
    if(head==NULL){
        printf("\nStack is empty");
    }
    else{
        printf("\nPeeked element is %d",head->data);
    }
}
void change(int ele){
    int temp;
    if(head==NULL){
        printf("\nStack is empty");
    }
    else{
        temp = head->data;
        head->data = ele;
        printf("\nElement %d is changed to %d",temp,head->data);
    }
}
void display(){
    struct Node *temp = (struct Node*)malloc(sizeof(struct Node));
    temp = head;
    if(head==NULL){
        printf("Underflow");
    }
    else{
        while(temp!=NULL){
            printf("\nValue is %d",temp->data);
            temp = temp->next;
        }
    }
    
}
int main(){
    char yn;
    int ch,ele;
    do{
        printf("\n 1: For Push\n 2: For Pop\n 3: For Peek\n 4: Change\n 5: Display\n Your choice:");
        scanf("%d",&ch);
        switch(ch){
            case 1: printf("\nEnter Element you want to push: ");
                    scanf("%d",&ele);
                    push(ele);
                    break;
            case 2: pop();
                    break;
            case 3: peep();
                    break;
            case 4: printf("\nEnter Element you want to change:");
                    scanf("%d",&ele);
                    change(ele);
                    break;
            case 5: display();
                    break;
        }
        printf("\n\nDo you want to continue? Enter Y for yes: ");
        scanf(" %c",&yn);

    }while(yn=='Y'||yn=='y');
    return 0;

}