From 2c8974b6c6cc0b9d9658e9e93c416c9abe288f8c Mon Sep 17 00:00:00 2001
From: fonkou <fonkoukamtewi@th-nuernberg.de>
Date: Tue, 25 Nov 2025 16:57:33 +0100
Subject: [PATCH 1/2] add typdef StackNode

---
 stack.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/stack.c b/stack.c
index e3a90d4..845f1a6 100644
--- a/stack.c
+++ b/stack.c
@@ -8,26 +8,23 @@
     * `clearStack`: gibt den gesamten Speicher frei. */
 
 // Pushes data as pointer onto the stack.
-StackNode *push(StackNode *stack, void *data)
-{
+typedef struct  Stack_node{
+    int *stackNode;
+}StackNode;
+
+StackNode *push(StackNode *stack, void *data) {
 
 }
 
 // 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)
-{
-
+StackNode *pop(StackNode *stack) {
 }
 
 // Returns the data of the top element.
-void *top(StackNode *stack)
-{
-
+void *top(StackNode *stack) {
 }
 
 // Clears stack and releases all memory.
-void clearStack(StackNode *stack)
-{
-
-}
\ No newline at end of file
+void clearStack(StackNode *stack) {
+}

From c2955be947df47d47f537abbb02bc7cbd5dbc571 Mon Sep 17 00:00:00 2001
From: fonkou <fonkoukamtewi@th-nuernberg.de>
Date: Tue, 2 Dec 2025 01:42:34 +0100
Subject: [PATCH 2/2] fix stac.c

---
 stack.c | 41 +++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/stack.c b/stack.c
index 845f1a6..c13df34 100644
--- a/stack.c
+++ b/stack.c
@@ -1,30 +1,43 @@
 #include <stdlib.h>
 #include "stack.h"
 
-//TODO: grundlegende Stackfunktionen implementieren:
-/*  * `push`: legt ein Element oben auf den Stack,
-    * `pop`: entfernt das oberste Element,
-    * `top`: liefert das oberste Element zurück,
-    * `clearStack`: gibt den gesamten Speicher frei. */
-
-// Pushes data as pointer onto the stack.
-typedef struct  Stack_node{
-    int *stackNode;
-}StackNode;
+typedef struct Stack_node {
+    void *data;
+    struct Stack_node *next;
+} StackNode;
 
+// Pushes data onto the stack.
+// Returns the new top of the stack.
 StackNode *push(StackNode *stack, void *data) {
+    StackNode *node = malloc(sizeof(StackNode));
+    if (!node) return stack;  // allocation failed → leave unchanged
 
+    node->data = data;
+    node->next = stack;
+    return node; // new top element
 }
 
-// Deletes the top element of the stack (latest added element) and releases its memory. (Pointer to data has to be
-// freed by caller.)
+// Deletes the top element and returns the new stack top.
+// Caller must free the *data* itself.
 StackNode *pop(StackNode *stack) {
+    if (!stack) return NULL;
+
+    StackNode *next = stack->next;
+    free(stack);   // free only the node, NOT the data
+    return next;
 }
 
-// Returns the data of the top element.
+// Returns the data at the top of the stack.
 void *top(StackNode *stack) {
+    if (!stack) return NULL;
+    return stack->data;
 }
 
-// Clears stack and releases all memory.
+// Clears entire stack (but does NOT free the data).
 void clearStack(StackNode *stack) {
+    while (stack) {
+        StackNode *next = stack->next;
+        free(stack);
+        stack = next;
+    }
 }