I need some help with generic linked list

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C++

C

Please modify the linked list as follows:
- assume list is homogeneous. Do not pass size for push method.
- For memory allocation and deallocation of the node data, the client will be responsible to implement a function for that and supply as a callback.

So, during insertion/deletion you call those callback functions.e.g., delete operation will take another param of function pointer type. And inside your delete function you will invoke the callback.

what I have implemented so far is given below

What I have tried:

// C program for generic linked list 
#include<stdio.h> 
#include<stdlib.h> 

/* A linked list node */
struct Node 
{ 
	// Any data type can be stored in this node 
	void *data; 

	struct Node *next; 
}; 

/* Function to add a node at the beginning of Linked List. 
This function expects a pointer to the data to be added 
and size of the data type */
void push(struct Node** head_ref, void *new_data, size_t data_size) 
{ 
	// Allocate memory for node 
	struct Node* new_node = (struct Node*)malloc(sizeof(struct Node)); 

	new_node->data = malloc(data_size); 
	new_node->next = (*head_ref); 

	// Copy contents of new_data to newly allocated memory. 
	// Assumption: char takes 1 byte. 
	int i; 
	for (i=0; i<data_size; i++) 
		*(char *)(new_node->data + i) = *(char *)(new_data + i); 

	// Change head pointer as new node is added at the beginning 
	(*head_ref) = new_node; 
} 

/* Function to print nodes in a given linked list. fpitr is used 
to access the function to be used for printing current node data. 
Note that different data types need different specifier in printf() */
void printList(struct Node *node, void (*fptr)(void *)) 
{ 
	while (node != NULL) 
	{ 
		(*fptr)(node->data); 
		node = node->next; 
	} 
} 

// Function to print an integer 
void printInt(void *n) 
{ 
printf(" %d", *(int *)n); 
} 

// Function to print a float 
void printFloat(void *f) 
{ 
printf(" %f", *(float *)f); 
} 

/* Driver program to test above function */
int main() 
{ 
	struct Node *start = NULL; 

	// Create and print an int linked list 
	unsigned int_size = sizeof(int); 
	int arr[] = {10, 20, 30, 40, 50}, i; 
	for (i=4; i>=0; i--) 
	push(&start, &arr[i], int_size); 
	printf("Created integer linked list is \n"); 
	printList(start, printInt); 

	// Create and print a float linked list 
	unsigned float_size = sizeof(float); 
	start = NULL; 
	float arr2[] = {10.1, 20.2, 30.3, 40.4, 50.5}; 
	for (i=4; i>=0; i--) 
	push(&start, &arr2[i], float_size); 
	printf("\n\nCreated float linked list is \n"); 
	printList(start, printFloat); 

	return 0; 
}