Add stack implementation

stack.c

+#include <stdio.h>
+#include <stdlib.h>
+
+typedef struct Node {
+    int data;
+    struct Node* before;
+} Node;
+
+Node* push(Node* node) {
+    int data;
+    printf("Data yang ini dimasukkan: "); scanf("%d", &data);
+    
+    Node* new = (Node*)malloc(sizeof(Node));
+    new->data = data;
+    new->before = node;
+    
+    return new;
+}
+
+Node* peek(Node* node) {
+    if(node == NULL) {
+        printf("Stack kosong\n\n");
+        return node;
+    }
+    printf("Data paling atas pada stack: %d\n", node->data);
+    return node;
+}
+
+Node* pop(Node* node) {
+    if(node == NULL) {
+        printf("Stack kosong\n\n");
+        return node;
+    }
+    Node* ptr = node;
+    node = node->before;
+    free(ptr);
+    printf("Data paling di stack paling atas telah dibuang\n");
+    return node;
+}
+
+Node* erase(Node* node) {
+    if(node == NULL) {
+        printf("Stack kosong\n\n");
+        return node;
+    }
+    while(node->before != NULL) {
+        Node* ptr = node;
+        node = node->before;
+        free(ptr);
+    }
+
+    free(node);
+    node = NULL;
+    return node;
+}
+
+Node* display(Node* node) {
+    if(node == NULL) {
+        printf("Tidak ada data\n");
+        return node;
+    }
+    Node* ptr = node;
+    int counter = 1;
+    while(node != NULL) {
+        printf("%d. %d\n", counter++, node->data);
+        node = node->before;
+    }
+    return ptr;
+}
+
+int main() {
+    Node* node = NULL;
+    int option;
+    do {
+        printf("Program stack\n");
+        printf("0. Display all stack data\n");
+        printf("1. Push operation\n");
+        printf("2. Peek operation\n");
+        printf("3. Pop operation\n");
+        printf("4. Delete all data\n");
+        printf("5. Keluar\n\n");
+        printf("Masukkan pilihan: ");
+        scanf("%d", &option);
+        switch (option)
+        {
+        case 0:
+            node = display(node);
+            break;
+        case 1:
+            node = push(node);
+            break;
+        case 2:
+            node = peek(node);
+            break;
+        case 3:
+            node = pop(node);
+            break;
+        case 4:
+            node = erase(node);
+            break;
+        }
+    } while(option != 5);
+
+    return 0;
+}
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