60 lines
1.5 KiB
C
60 lines
1.5 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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//pointer onto new struct
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StackNode* newNode = malloc(sizeof(StackNode));
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newNode->data = data;
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//*stack := first node of the stack; is now the second to first node
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newNode->nextNode = stack;
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return newNode;
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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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//getting the second to first node
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StackNode* tmp = stack->nextNode;
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// data should be freed by the caller
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// free(stack->data);
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// stack->data = NULL;
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free(stack);
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stack = NULL;
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return tmp;
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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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//No stack --> No data-pointer
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if (stack == NULL) return NULL;
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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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if (stack == NULL) return;
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if (stack->nextNode != NULL) clearStack(stack->nextNode);
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// date should be freed by the caller.
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// free(stack->data);
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// stack->data = NULL;
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free(stack);
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// technically not needed (dangling pointer)
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stack = NULL;
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} |