47 lines
1.1 KiB
C
47 lines
1.1 KiB
C
#include <stdlib.h>
|
|
#include "stack.h"
|
|
|
|
// Pushes data as pointer onto the stack.
|
|
StackNode *push(StackNode *stack, void *data)
|
|
{
|
|
StackNode *node = (StackNode *)malloc(sizeof(StackNode));
|
|
if(node == NULL)
|
|
return stack; // allocation failed -> return unchanged stack
|
|
|
|
node->data = data;
|
|
node->next = stack;
|
|
return node;
|
|
}
|
|
|
|
// Deletes the top element of the stack (latest added element) and releases its memory. (Pointer to data has to be
|
|
// freed by caller.)
|
|
StackNode *pop(StackNode *stack)
|
|
{
|
|
if(stack == NULL)
|
|
return NULL;
|
|
|
|
StackNode *next = stack->next;
|
|
// Do NOT free stack->data here; caller owns the pointed data
|
|
free(stack);
|
|
return next;
|
|
}
|
|
|
|
// Returns the data of the top element.
|
|
void *top(StackNode *stack)
|
|
{
|
|
if(stack == NULL)
|
|
return NULL;
|
|
return stack->data;
|
|
}
|
|
|
|
// Clears stack and releases all memory.
|
|
void clearStack(StackNode *stack)
|
|
{
|
|
while(stack != NULL)
|
|
{
|
|
StackNode *next = stack->next;
|
|
// Do NOT free stack->data here; caller owns the pointed data
|
|
free(stack);
|
|
stack = next;
|
|
}
|
|
} |