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peek_operation_stack.c
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peek_operation_stack.c
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#include<stdio.h>
#include<stdlib.h>
struct stack
{
int size;
int top;
int * arr;
// struct stack *arr;
};
int isEmpty(struct stack * ptr)
{
if (ptr->top == -1)
{
return 1; // this means TRUE
}
return 0; //this means FALSE
}
int isFull(struct stack *ptr){
if (ptr->top == (ptr->size - 1))
{
return 1;
}
return 0;
}
//23-07-2021
void push(struct stack *ptr, int val){
if (isFull(ptr))
{
printf("Stack Overflowed!!");
}
ptr->top++;
ptr->arr[ptr->top] = val;
}
int pop(struct stack *ptr){
if (isEmpty(ptr))
{
printf("Stack is Underflowed!!");
return -1;
}
int val = ptr->arr[ptr->top];
ptr->top--;
return val;
}
//24-07-2021
int peek(struct stack *ptr, int i){
int arrId = ptr->top -i + 1;
if (arrId < 0)
{
printf("Not a Valid position");
return -1;
}
return ptr->arr[arrId];
}
int main(){
struct stack * sp = (struct stack*)malloc(sizeof(struct stack));
sp->size = 10;
sp->top = -1;
sp->arr = (int *)malloc(sp->size * sizeof(int));
push(sp, 69);
push(sp, 420);
push(sp, 666);
push(sp, 645);
push(sp, 466);
printf("%d\n",peek(sp, 3));
for (int i = 1; i <= (sp->top + 1); i++)
{
printf("%d\n",peek(sp, i));
}
return 0;
}