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#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include "util.h"
typedef int T;
struct stack {
T *array;
size_t sz, p;
};
void
stack_init(struct stack *stack)
{
stack->array = NULL;
stack->sz = 0;
stack->p = 0;
}
bool
stack_push(struct stack *stack, T data)
{
if ( stack->array == NULL ) {
if ( (stack->array = malloc(10 * sizeof(*stack->array))) != NULL ) {
stack->sz = 10;
stack->p = 0;
}
else {
ERROR("out of memory");
return false;
}
}
if ( stack->p == stack->sz ) {
size_t new_sz;
T *new_array;
if ( (new_array = realloc(stack->array, (new_sz = (stack->sz * 3 / 2)) * sizeof(*stack->array))) != NULL ) {
stack->array = new_array;
stack->sz = new_sz;
}
else {
ERROR("out of memory");
return false;
}
}
stack->array[stack->p++] = data;
return true;
}
bool
stack_pop(struct stack *stack, T *data)
{
if ( stack->p != 0 ) {
*data = stack->array[--stack->p];
return true;
}
else
return false;
}
bool
stack_empty(struct stack *stack)
{
return stack->p == 0;
}
void
stack_free(struct stack *stack)
{
free(stack->array);
}
int
main()
{
struct stack stack[1];
stack_init(stack);
for ( int i = 0; i != 20; ++i )
stack_push(stack, i);
while ( !stack_empty(stack) ) {
int i;
if ( stack_pop(stack, &i) )
printf("%d\n", i);
else
ERROR("this shouldn't happen!");
}
stack_free(stack);
return EXIT_SUCCESS;
}
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