62 lines
1.4 KiB
C
62 lines
1.4 KiB
C
#include <stdlib.h>
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#include "stack.h"
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//TODO: grundlegende Stackfunktionen implementieren:
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/* * `push`: legt ein Element oben auf den Stack,
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* `pop`: entfernt das oberste Element,
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* `top`: liefert das oberste Element zurück,
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* `clearStack`: gibt den gesamten Speicher frei. */
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// Pushes data as pointer onto the stack.
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StackNode *push(StackNode *stack, void *data)
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{
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// Neues Stack-Element erstellen
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StackNode *newNode = malloc(sizeof(StackNode));
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if (!newNode) {
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return stack; // oder NULL, je nach Fehlerstrategie
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}
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newNode->data = data;
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newNode->next = stack; // bisheriger Stack wird nach unten geschoben
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return newNode; // neuer Kopf des Stacks
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}
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// Deletes the top element of the stack (latest added element) and releases its memory. (Pointer to data has to be
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// freed by caller.)
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StackNode *pop(StackNode *stack)
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{
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if (stack == NULL)
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return NULL;
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StackNode *newTop = stack->next;
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free(stack);
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return newTop;
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}
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// Returns the data of the top element.
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void *top(StackNode *stack)
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{
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if (stack == NULL)
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return NULL; // kein Element im Stack
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return stack->data;
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}
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// Clears stack and releases all memory.
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void clearStack(StackNode *stack)
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{
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StackNode *current = stack;
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while (current != NULL)
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{
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StackNode *next = current->next;
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free(current);
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current = next;
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}
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} |