47 lines
1.2 KiB
C
47 lines
1.2 KiB
C
#include <stdlib.h>
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#include "stack.h"
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// Push Daten auf den Stack legen.
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StackNode *push(StackNode *stack, void *data)
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{
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StackNode *node = (StackNode *)malloc(sizeof(StackNode));
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if(node == NULL)
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return stack; // allocation failed -> return unchanged stack
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node->data = data; // Set the data for the new node
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node->next = stack; // New node points to the previous top of the stack
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return node;
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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 *next = stack->next;
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// Do NOT free stack->data here; caller owns the pointed data
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free(stack);
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return next;
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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;
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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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while(stack != NULL)
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{
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StackNode *next = stack->next;
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// Do NOT free stack->data here; caller owns the pointed data
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free(stack);
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stack = next;
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}
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} |