91 lines
1.7 KiB
C
91 lines
1.7 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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StackNode *tempNode, *newNode;
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newNode = malloc(sizeof(StackNode));
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newNode->value = *(int *)data;
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newNode->next = NULL;
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if (stack == NULL)
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{
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stack = newNode;
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return stack;
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}
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tempNode = stack;
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while (tempNode->next != NULL)
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{
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tempNode = tempNode->next;
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}
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tempNode->next = newNode;
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return stack;
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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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StackNode *tempNode;
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if (stack == NULL)
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{
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return stack;
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}
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tempNode = stack;
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while (tempNode->next->next != NULL)
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{
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tempNode = tempNode->next;
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}
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free(tempNode->next);
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tempNode->next = NULL;
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return stack;
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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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StackNode *tempNode;
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if (stack == NULL)
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{
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return NULL;
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}
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tempNode = stack;
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while (tempNode->next != NULL)
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{
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tempNode = tempNode->next;
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}
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return &tempNode->value;
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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 *tempNode;
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if (stack == NULL)
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{
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return;
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}
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tempNode = stack;
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while (tempNode != NULL)
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{
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tempNode = pop(tempNode);
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}
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} |