Counting nodes in a linked list is very useful while working on it. It requires creating a temp node pointing to the head of the list and a variable called i with initial value 0. If the temp node is not null, increase i by 1 and move to the next node using temp next. Repeat the process till the temp node becomes null. The final value of i will be the total number of nodes in the linked list.

The function countNodes is created for this purpose. It is a 4-step process.

```int countNodes() {

//1. create a temp node pointing to head
Node* temp = head;

//2. create a variable to count nodes
int i = 0;

//3. if the temp node is not null increase
//   i by 1 and move to the next node, repeat
//   the process till the temp becomes null
while(temp != NULL) {
i++;
temp = temp->next;
}

//4. return the count
return i;
}
```

The below is a complete program that uses above discussed concept of counting the total number of nodes of a linked list.

```#include <iostream>
using namespace std;

//node structure
struct Node {
int data;
Node* next;
};

class LinkedList {
private:
Node* head;
public:
LinkedList(){
head = NULL;
}

//Add new element at the end of the list
void push_back(int newElement) {
Node* newNode = new Node();
newNode->data = newElement;
newNode->next = NULL;
if(head == NULL) {
head = newNode;
} else {
Node* temp = head;
while(temp->next != NULL)
temp = temp->next;
temp->next = newNode;
}
}

//count nodes in the list
int countNodes() {
Node* temp = head;
int i = 0;
while(temp != NULL) {
i++;
temp = temp->next;
}
return i;
}

//display the content of the list
void PrintList() {
Node* temp = head;
if(temp != NULL) {
cout<<"\nThe list contains: ";
while(temp != NULL) {
cout<<temp->data<<" ";
temp = temp->next;
}
} else {
cout<<"\nThe list is empty.";
}
}
};

// test the code
int main() {
LinkedList MyList;

//Add four elements in the list.
MyList.push_back(10);
MyList.push_back(20);
MyList.push_back(30);
MyList.push_back(40);

//Display the content of the list.
MyList.PrintList();

//number of nodes in the list
cout<<"\nNo. of nodes: "<<MyList.countNodes();

return 0;
}
```

The above code will give the following output:

```The list contains: 10 20 30 40
No. of nodes: 4
```