Algorithm for implementation of stack using pointers?

Answer 1

#include<stdio.h>

#include<conio.h>

struct node

{

int data;

struct node *next;

};

typedef struct node NODE;

NODE* top = NULL;

void push()

{

NODE* temp;

int item;

temp = (NODE*)malloc (sizeof(NODE));

printf("Enter the item to be inserted-> ");

scanf("%d",&item);

temp->data = item;

temp->next = NULL;

if(top NULL)

{

printf("\n***Stack is empty***\n");

return;

}

else

{

temp = top;

printf("\nThe list is-> ");

while(temp != NULL)

{

printf("\t%d",temp->data);

temp = temp->next;

}

printf("\n");

}

}

int main()

{

int OP;

clrscr();

while(1)

{

printf("\n>>>CHOOSE OPTION<<<\n");

printf("\n 1.PUSH \n\n 2.POP \n\n 3.TRAVERSE \n\n 4.EXIT\n");

scanf("%d",&OP);

switch(OP)

{

case 1: push();

break;

case 2: pop();

break;

case 3: display();

break;

case 4: exit(1);

default:printf("\n\n\t<<WRONG OPTION PLEASE CHOOSE CORRECT OPTION>>\n\n");

break;

}

};

getch();

return 0;

}

Answer 2

#include #include #include #define MAX 50 int size; /* Defining the stack structure */ struct stack { intarr[MAX]; int top; }; /* Initializing the stack(i.e., top=-1) */ void init_stk(struct stack *st) { st->top = -1; } /* Entering the elements into stack */ void push (struct stack *st,int num) { if(st->top == size-1) { printf("nStack overflow(i.e., stack full)."); return; } st->top++; st->arr[st->top] = num; } //Deleting an element from the stack. int pop(struct stack *st) { int num; if(st->top == -1) { printf("nStack underflow(i.e., stack empty)."); return NULL; } num = st->arr[st->top]; st->top--; return num; } voiddisplay(struct stack *st) { int i; for(i=st->top;i>=0;i--) printf("n%d",st->arr[i]); } int main() { int element,opt,val; struct stack ptr; init_stk(&ptr); printf("nEnter Stack Size :"); scanf("%d",&size); while(1) { printf("nntSTACK PRIMITIVE OPERATIONS"); printf("n1.PUSH"); printf("n2.POP"); printf("n3.DISPLAY"); printf("n4.QUIT"); printf("n"); printf("nEnter your option : "); scanf("%d",&opt); switch(opt) { case 1: printf("nEnter the element into stack:"); scanf("%d",&val); push(&ptr,val); break; case 2: element = pop(&ptr); printf("nThe element popped from stack is : %d",element); break; case 3: printf("nThe current stack elements are:"); display(&ptr); break; case 4: exit(0); default: printf("nEnter correct option!Try again."); } } return(0); }