Generic stack in C

01. DataStructures/02. Stack/Basic Operation/5.Generic Stack/generic_stack.c

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+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#include<stdbool.h>
+
+typedef struct _stack_ {
+	void* data;
+	struct _stack_ *next;
+} Stack;
+
+/**
+ * Element to be added to the stack
+ */
+typedef struct _user{
+	char *name;
+	int age;
+} User;
+
+/**
+ * Another Element to be added to the stack
+ */
+typedef struct _vehicle{
+    char *brand;
+	char *model;
+    char *color;
+} Vehicle;
+
+
+/// <summary>
+/// Check if the list is empty
+/// </summary>
+/// <param name="st"></param>
+/// <returns></returns>
+bool isEmpty(Stack* st) {
+    return st == NULL ? true : false;
+}
+
+/// <summary>
+/// Create a Node
+/// </summary>
+/// <param name="st"></param>
+/// <param name="value"></param>
+/// <returns></returns>
+Stack* createNode(Stack* st, void* data) {
+    st = (Stack*)malloc(sizeof(Stack));
+    st->data = data;
+    st->next = NULL;
+    return st;
+}
+
+/// <summary>
+/// Push the element to the stack
+/// </summary>
+/// <param name="st"></param>
+/// <param name="value"></param>
+/// <returns></returns>
+Stack* push(Stack* st, void* data) {
+    if (st == NULL) {
+        st = createNode(st, data);
+    }
+    else {
+        Stack* newNode = NULL;
+        newNode = createNode(newNode, data);
+        newNode->next = st;
+        return newNode;
+    }
+    return st;
+}
+
+/// <summary>
+/// Pop the element to the stack
+/// </summary>
+/// <param name="st"></param>
+/// <returns></returns>
+Stack* pop(Stack* st) {
+    void* data = NULL;
+    Stack* auxNode;
+    if (isEmpty(st)) {
+        printf("Stack is underflow");
+    }
+    else {
+        data = st->data;
+        auxNode = st;
+        st = st->next;
+        free(auxNode);
+    }   
+    return st;
+}
+
+
+/// <summary>
+/// Get the most top element to the stack
+/// </summary>
+/// <param name="st"></param>
+/// <returns></returns>
+void* top(Stack st) {
+    if(isEmpty(&st))
+        return NULL;
+    return st.data;
+}
+
+/// <summary>
+/// Get the element at the given position
+/// </summary>
+/// <param name="st"></param>
+/// <param name="pos"></param>
+/// <returns></returns>
+void* peek(Stack st, int pos) {
+    Stack* node = &st;
+    if (isEmpty(&st))
+        return NULL;
+    for (int i = 0; i < pos && node != NULL; i++) {
+        node = node->next;
+    }
+    return node != NULL ? node->data : NULL;
+}
+
+void display(void *data, void (*displayFunc)(void*)) {
+    displayFunc(data);
+}
+
+void displayUser(void* data) {
+    User* user = (User*)data;
+    if(user!= NULL) {
+        printf("Name: %s Age %d\n",user->name, user->age);
+    }
+}
+
+void displayVehicle(void* data) {
+    Vehicle* vehicle = (Vehicle*)data;
+    if(vehicle!= NULL) {
+        printf("Brand: %s Model: %s Color: %s\n",vehicle->brand, vehicle->model, vehicle->color);
+    }
+}
+
+
+
+int main()
+{
+    Stack* stl = NULL;
+    User* user = (User*)malloc(sizeof(User));
+    user->name = "john Doe";
+    user->age = 25;
+    Vehicle* vehicle = (Vehicle*)malloc(sizeof(Vehicle));
+    vehicle->brand = "Jia";
+    vehicle->model = "Rio";
+    vehicle->color = "Red";
+    stl = push(stl, vehicle);
+    stl = push(stl, user);
+
+    display(top(*stl), &displayUser);
+    display(top(*stl->next), &displayVehicle);
+    return 0;
+}