Programming Articles - Page 2728 of 3363

A class constructor is a special member function of a class that is executed whenever we create new objects of that class.A constructor will have exact same name as the class and it does not have any return type at all, not even void. Constructors can be very useful for setting initial values for certain member variables.Following example explains the concept of constructor −Example Live Demo#include using namespace std; class Line {    public:       void setLength( double len );       double getLength( void );       Line(); // This is the constructor       private:       double length; }; // Member functions definitions including constructor Line::Line(void) {    cout

You can add a not null constraint to a column of a table using the ALTER TABLE command.SyntaxALTER TABLE table_name MODIFY column_name datatype NOT NULL;Assume we have a table named Dispatches in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location with description as shown below:+--------------+--------------+------+-----+---------+-------+ | Field        | Type         | Null | Key | Default | Extra | +--------------+--------------+------+-----+---------+-------+ | ProductName  | varchar(255) | YES  |     | NULL    |       | | CustomerName | varchar(255) | YES  |     | NULL   ... Read More

In this article, we will write a C++ program that implements a Min Heap. A Min Heap is a binary tree where the value of each node is less than or equal to the values of its children. We will explain how to create a Min Heap using arrays and implement operations like insertion and deletion. The article will cover the following topics: What is a Heap? Types of Heap Representing a Heap What is a Min Heap? What ... Read More

You can add a unique constraint to a column using the ALTER TABLE commandSyntaxALTER TABLE table_name ADD CONSTRAINT MyUniqueConstraint UNIQUE(column1, column2...);Assume we have a table named Dispatches in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location with description as shown below:+--------------+--------------+------+-----+---------+-------+ | Field        | Type         | Null | Key | Default | Extra | +--------------+--------------+------+-----+---------+-------+ | ProductName  | varchar(255) | YES  |     | NULL    | | | CustomerName | varchar(255) | No   |     | NULL ... Read More

In this article, we will write a C++ program that implements a Max Heap. A Max Heap is a binary tree where the value of each node is greater than or equal to the values of its children. We will explain how to create a Max Heap using arrays and implement operations like insertion and deletion. The article will cover the following topics: What is a Heap? What is Max Heap? What is Heapify? Max Heap Implementation Deletion from ... Read More

You can add a primary key constraint to a column of a table using the ALTER TABLE command.SyntaxALTER TABLE table_name ADD CONSTRAINT MyPrimaryKey PRIMARY KEY (column1, column2...);Assume we have a table named Dispatches in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location with description as shown below:+--------------+--------------+------+-----+---------+-------+ | Field        | Type         | Null | Key | Default | Extra | +--------------+--------------+------+-----+---------+-------+ | ProductName  | varchar(255) | YES  |     | NULL | | | CustomerName | varchar(255) | ... Read More

A Binary Heap is a complete binary tree which is either Min Heap or Max Heap. In a Max Binary Heap, the key at root must be maximum among all keys present in Binary Heap. This property must be recursively true for all nodes in that Binary Tree. Min Binary Heap is similar to MinHeap.Function descriptions:void BHeap::Insert(int ele): Perform insertion operation to insert element in heap.void BHeap::DeleteMin(): Perform deleteion operation to delete minimum value from heap.int BHeap::ExtractMin(): Perfrom operation to extract minimum value from heap.void BHeap::showHeap(): To show the elements of heap.void BHeap::heapifyup(int in): maintain heap structure in bottom up ... Read More

ReferencesWhen a variable is declared as reference, it becomes an alternative name for an existing variable.SyntaxType &newname = existing name;InitializatioType &pointer; pointer = variable name;PointersPointers are used to store the address of variable.SyntaxType *pointer;InitializationType *pointer; pointer = variable name;The main differences between references and pointers are -References are used to refer an existing variable in another name whereas pointers are used to store address of variable.References cannot have a null value assigned but pointer can.A reference variable can be referenced by pass by value whereas a pointer can be referenced but pass by reference.A reference must be initialized on declaration ... Read More

In C++, both pointers and references are used to access and manipulate memory. But they behave differently. This guide explains each with simple words and examples. We understand the topic by learning how each is declared, used, and what differences exist between them. What are C++ Pointers? The pointers are used to store the address of a variable. We can change what they pointing to, and also can assign NULL to them. A pointer is similar to a signpost that contains the memory address of another variable, and you can directly access or change the variable by its address. Syntax ... Read More

You can delete a column in a table using the ALTER TABLE command.SyntaxALTER TABLE table_name DROP COLUMN column_name;Assume we have a table named Sales in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location as shown below:+----+-------------+--------------+--------------+--------------+-------+----------------+ | id | productname | CustomerName | DispatchDate | DeliveryTime | Price | Location     | +----+-------------+--------------+--------------+--------------+-------+----------------+ | 1  | Key-Board   | Raja         | 2019-09-01   | 08:51:36     | 7000  | Hyderabad      | | 2  | Earphones   | Roja         | 2019-05-01   ... Read More