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Do-while Loop Statement The do-while loop is similar to the while loop, except that the test condition is performed at the end of the loop instead of at the beginning. The do—while loop executes atleast once without checking the condition. It begins with the keyword do, followed by the statements that making up the body of the loop. Finally, the keyword while and the test expression completes the do-while loop. When the loop condition becomes false, the loop is terminated and execution continues with the statement immediately following the loop. The syntax of the do-while loop is do while (); The following program explains the do--while statement. public class DoWhileLoopDemo { public static void main(String[] args) { int count = 1; System.out.println(“Printing Numbers from 1 to 10”); do { System.out.println(count++); } while (count <= 10); } } Thanks 🙏😊

Objects And Classes Object Objects have states and behaviors. Example: A dog has states - color, name, breed as well as behaviors – wagging the tail, barking, eating. An object is an instance of a class. Class A class can be defined as a template/blueprint that describes the behavior/state that the object of its type support. Objects in Java If we consider the real-world, we can find many objects around us, cars, dogs, humans, etc. All these objects have a state and a behavior. If we consider a dog, then its state is - name, breed, color, and the behavior is - barking, wagging the tail, running. If we compare the software object with a real-world object, they have very similar char￾acteristics. Software objects also have a state and a behavior. A software object’s state is stored in fields and behavior is shown via methods. So in software development, methods operate on the internal state of an object and the object-to-object communication is done via methods.

Static Keyword The static keyword indicates that the member belongs to the class instead of a specific instance. It is used to create class variable and mainly used for memory management. The static keyword can be used with: • Variable (static variable or class variable) • Method (static method or class method) • Block (static block) • Nested class (static class) • import (static import) Static variable Variable declared with keyword static is a static variable. It is a class level variable com￾monly shared by all objects of the class. • Memory allocation for such variables only happens once when the class is loaded in the memory. • scope of the static variable is class scope ( accessible only inside the class) • lifetime is global ( memory is assigned till the class is removed by JVM). • Automatically initialized to 0. • It is accessible using ClassName.variablename • Static variables can be accessed directly in static and non-static methods

The Task of a Constructor Traditional programming languages only allocate memory for a variable being defined. The programmer must ensure that the variable is initialized with suitable values. An object of the class Account, as described in the previous chapter, does not possess any valid values until the method init() is called. Non-initialized objects can lead to serious runtime errors in your programs. To avoid errors of this type, C++ performs implicit initialization when an object is defined. This ensures that objects will always have valid data to work on. Initialization is performed by special methods known as constructors. Declaration Constructors can be identified by their names. In contrast to other member functions, the following applies: ■ the name of the constructor is also the class name ■ a constructor does not possess a return type—not even void. Constructors are normally declared in the public section of a class. This allows you to create objects wherever the class definition is available. Constructors can be overloaded, just like other functions. Constructors belonging to a class must be distinguishable by their signature (that is, the number, order, and type of parameters). This allows for different methods of object initialization. The example opposite shows an addition to the Account class. The class now has two constructors. Definition Since a constructor has the same name as its class, the definition of a constructor always begins with Class_name::Class_name In the definition itself, the arguments passed can be checked for validity before they are copied to the corresponding data members. If the number of arguments is smaller than the number of data members, the remaining members can be initialized using default val￾ues. Constructors can also perform more complex initialization tasks, such as opening files, allocating memory, and configuring interfaces. @Ethiopian programmer

1 👉Data Abstraction Humans use abstraction in order to manage complex situations. Objects and processes are reduced to basics and referred to in generic terms. Classes allow more direct use of the results of this type of abstraction in software development. The first step towards solving a problem is analysis. In object-oriented programming, analysis comprises identifying and describing objects and recognizing their mutual rela￾tionships. Object descriptions are the building blocks of classes. In C++, a class is a user-defined type. It contains data members, which describe the properties of the class, and member functions, or methods, which describe the capacities of the objects. Classes are simply patterns used to instantiate, or create, objects of the class type. In other words, an object is a variable of a given class. 2 👉 Data Encapsulation When you define a class, you also specify the private members, that is, the members that are not available for external access, and the public members of that class. An applica￾tion program accesses objects by using the public methods of the class and thus activat￾ing its capacities. Access to object data is rarely direct, that is, object data is normally declared as pri￾vate and then read or modified by methods with public declarations to ensure correct access to the data. One important aspect of this technique is the fact that application programs need not be aware of the internal structure of the data. If needed, the internal structure of the pro￾gram data can even be modified. Provided that the interfaces of the public methods remain unchanged, changes like these will not affect the application program. This allows you to enhance an application by programming an improved class version without changing a single byte of the application. An object is thus seen to encapsulate its private structure, protecting itself from exter￾nal influences and managing itself by its own methods. This describes the concept of data encapsulation concisely @Ethiopian programmer 😊

Margaret Hamilton, née Margaret Heafield, (born August 17, 1936, Paoli, Indiana, U.S.), American computer scientist who was one of the first computer software programmers; she created the term software engineer to describe her work. THAT'S WHY PROGRAMMING IS DIFFICULT TO UNDERSTAND🤣🤣🤣 HAVE A NICE DREAM 🙏

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Passing by Reference A pass by reference can be programmed using references or pointers as function parame￾ters. It is syntactically simpler to use references, although not always permissible. A parameter of a reference type is an alias for an argument. When a function is called, a reference parameter is initialized with the object supplied as an argument. The function can thus directly manipulate the argument passed to it. Example: void test( int& a) { ++a; } Based on this definition, the statement test( var); // For an int variable var increments the variable var. Within the function, any access to the reference a auto￾matically accesses the supplied variable, var. If an object is passed as an argument when passing by reference, the object is not copied. Instead, the address of the object is passed to the function internally, allowing the function to access the object with which it was called. Comparison to Passing by Value In contrast to a normal pass by value an expression, such as a+b, cannot be used as an argument. The argument must have an address in memory and be of the correct type. Using references as parameters offers the following benefits: ■ arguments are not copied. In contrast to passing by value, the run time of a pro￾gram should improve, especially if the arguments occupy large amounts of mem￾ory ■ a function can use the reference parameter to return multiple values to the calling function. Passing by value allows only one result as a return value, unless you resort to using global variables. If you need to read arguments, but not copy them, you can define a read-only reference as a parameter. Example: void display( const string& str); The function display() contains a string as an argument. However, it does not gener￾ate a new string to which the argument string is copied. Instead, str is simply a refer￾ence to the argument. The caller can rest assured that the argument is not modified within the function, as str is declared as a const.