What is the difference between a variable and an identifier?
I am a new programmer and I am currently learning Python programming language. I am currently engaged in a particular task in which I need to store and manipulate various pieces of data. During a session, my mentor asked me to explain what I understood about variables and identifiers. For this, I have created the following code snippet:
In the context of Python programming language, here is the difference given between variable and identifier:-
A variable is a storage location in the memory that can hold a value. It can also store the data which can be changed during the implementation of a program. The identifier is a name used in identifying a variable, function, class, module, or even other objects.
“item_count” is the identifier for the variable storing the value 5. While the “item_price” is the identifier for the variable storing the value 10.99.
The “total_cost” is the identifier for the variable which stores the results of “item_count and item_price”.
To change the “total_cost” to the “final_amount,” you should first try to identify all the Instances of the “total_cost” in the code. Now you should replace each instance of “total_cost” with the “final_amount”. Therefore, the update would look like this:-
Item_count = 5
Item_price = 10.99
Final_amount = item_count * item_priceThis would ensure that the new identifier “final_anount” is used consistently throughout the code which would help in maintaining the functionality of the program.
Here is an example given in Java programming language:-
Class Book {
// Attributes (variables)
Private String title;
Private String author;
Private double price;
Private int quantity;
// Constructor
Public Book(String title, String author, double price, int quantity) {
This.title = title;
This.author = author;
This.price = price;
This.quantity = quantity;
}
// Getter and Setter methods
Public String getTitle() {
Return title;
}
Public String getAuthor() {
Return author;
}
Public double getPrice() {
Return price;
}
Public int getQuantity() {
Return quantity;
}
Public void setQuantity(int quantity) {
This.quantity = quantity;
}
@Override
Public String toString() {
Return “Title: “ + title + “, Author: “ + author + “, Price: $” + price + “, Quantity: “ + quantity;
}
}
Class Inventory {
Private ArrayList books;
// Constructor
Public Inventory() {
Books = new ArrayList<>();
}
// Add a book to the inventory
Public void addBook(Book book) {
Books.add(book);
}
// Remove a book from the inventory
Public boolean removeBook(String title) {
For (Book book : books) {
If (book.getTitle().equalsIgnoreCase(title)) {
Books.remove(book);
Return true;
}
}
Return false;
}
// Search for a book by title
Public Book searchBook(String title) {
For (Book book : books) {
If (book.getTitle().equalsIgnoreCase(title)) {
Return book;
}
}
Return null;
}
// Display all books in the inventory
Public void displayBooks() {
If (books.isEmpty()) {
System.out.println(“The inventory is empty.”);
} else {
For (Book book : books) {
System.out.println(book);
}
}
}
}
Public class BookstoreInventory {
Public static void main(String[] args) {
Inventory inventory = new Inventory();
// Creating book objects
Book book1 = new Book(“To Kill a Mockingbird”, “Harper Lee”, 18.99, 10);
Book book2 = new Book(“1984”, “George Orwell”, 15.99, 5);
Book book3 = new Book(“The Great Gatsby”, “F. Scott Fitzgerald”, 10.99, 2);
// Adding books to inventory
Inventory.addBook(book1);
Inventory.addBook(book2);
Inventory.addBook(book3);
// Displaying all books
System.out.println(“Books in inventory:”);
Inventory.displayBooks();
// Searching for a book
System.out.println(“
Searching for ‘1984’:”);
Book foundBook = inventory.searchBook(“1984”);
If (foundBook != null) {
System.out.println(“Found: “ + foundBook);
} else {
System.out.println(“Book not found.”);
}
// Removing a book
System.out.println(“
Removing ‘The Great Gatsby’:”);
Boolean isRemoved = inventory.removeBook(“The Great Gatsby”);
If (isRemoved) {
System.out.println(“Book removed successfully.”);
} else {
System.out.println(“Book not found.”);
}
// Displaying all books after removal
System.out.println(“
Books in inventory after removal:”);
Inventory.displayBooks();
}
}