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#include "stack.h"
#include <stdio.h>
#include <stdlib.h>
// Error handler for stack errors
void stack_error(int id)
{
switch (id)
{
case 0:
printf("Error: Stack overflow\nBe kind and report this problem.");
break;
case 1:
printf("Error: Stack underflow\nBe kind and report this problem.");
break;
}
exit(1);
}
// Creates a new stack
struct stack *create_stack(int capacity)
{
struct stack *pt = (struct stack *)malloc(sizeof(struct stack));
pt->max_size = capacity;
pt->top = -1;
pt->items = (int *)malloc(sizeof(int) * capacity);
return pt;
}
// Adds a new item to a stack
void stack_push(struct stack *pt, int x)
{
// Avoid a overflow by checking if the stack is full
if (pt->top == pt->max_size - 1)
stack_error(0);
// Add an element and increase the top index
pt->items[++pt->top] = x;
}
// Returns the topmost item of a stack
int stack_peek(struct stack *pt)
{
// Check if the stack is empty
if (pt->top == -1)
stack_error(1);
return pt->items[pt->top];
}
// Deletes the topmost item of a stack
int stack_pop(struct stack *pt)
{
// Check for a stack underflow
if (pt->top == -1)
stack_error(0);
// Decrease the stack size by 1 and (optionally) return the popped element
return pt->items[pt->top--];
}
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