C++, Java, and .NET Programming Concepts

Option A correctly uses LINQ to DataSet syntax in VB.NET with AsEnumerable() to enable LINQ queries on DataTable rows. The Select clause returns all product rows which can then be iterated to display product names. Option B has invalid syntax, Option C uses a different alias but doesn't address displaying names specifically.

LINQ to SQL uses SubmitChanges() to write pending insert, update, and delete operations to the database. The framework tracks changes to entities and automatically generates and executes appropriate SQL commands when SubmitChanges() is called. The other methods are not part of LINQ to SQL.

SqlDataView is not a valid ADO.NET class. DataView is the correct class name and is provider-independent. SqlDataAdapter, SqlConnection, and SqlDataReader are all legitimate SQL Server-specific ADO.NET objects found in System.Data.SqlClient namespace.

SqlCommand inherits CreateObjRef from MarshalByRefObject (base class of all .NET objects), implements BeginExecuteNonQuery for asynchronous query execution, and has Prepare to optimize parameterized commands. All three are valid methods available on a SqlCommand object.

The statement is syntactically correct in C#. A char can be compared with a numeric literal - the char is implicitly converted to its integer Unicode value (100 for 'd'), then compared to 32.00. The comparison evaluates to false, but the code compiles and runs without error.

Java evaluates arithmetic expressions from left to right. In 1+2+"3", the integers 1 and 2 are added to get 3, which is concatenated with "3" to yield "33". In "1"+2+3, the string "1" is concatenated with 2 and then 3, producing "123".

In Java, dividing a floating-point number by zero does not throw an exception. Instead, it produces positive or negative infinity (Float.POSITIVE_INFINITY in this case). Only integer division by zero throws ArithmeticException. Therefore the statement does NOT throw an exception, making 'False' the correct answer.

The ternary operator (a>b)?a:b avoids method call overhead and is executed inline by the JVM. Math.max() requires a method invocation, which involves stack frame creation and overhead even if the JIT compiler eventually inlines it. For simple comparisons, the ternary is measurably faster.

Macro functions (created with #define) are expanded by the preprocessor before compilation begins, resulting in text substitution. Inline functions are expanded by the compiler during compilation, with the inline keyword being a hint (not a guarantee) for function call replacement. Option A is wrong because it misstates when inline expansion occurs. Option C reverses the correct phases.

The class my_class contains two int data members (x and y). Given that int occupies 2 bytes, the total size is 2 + 2 = 4 bytes. Member functions (add, display) do not contribute to object size as they are stored once in the code segment, not per object instance. Options B, C, and D incorrectly add extra bytes for member functions or padding.

An abstract class in C++ is a class that contains at least one pure virtual function and cannot be instantiated directly - meaning you cannot create objects of the abstract class type itself. However, you CAN create pointers/references to it, and you MUST derive from it to create objects of the derived classes. Option A is incorrect because abstract classes are designed to be inherited. Option D is wrong because abstract classes can inherit from other classes.

Dynamic binding (also called runtime polymorphism) in C++ is achieved through virtual functions. When a function is declared virtual, the compiler creates a vtable (virtual table) for the class, and function calls are resolved at runtime based on the actual object type rather than the pointer/reference type. Method overloading and operator overloading are compile-time polymorphism (static binding), not dynamic.

Constructors CANNOT be virtual because they initialize objects and virtual dispatch mechanisms (vtables) aren't available until after construction completes. Destructors CAN and SHOULD be virtual when a class is designed for polymorphism to ensure proper cleanup of derived class resources. Constructors CAN be overloaded (multiple constructors with different parameters). Virtual functions have slight performance overhead due to vtable lookup, so they're slower than direct function calls.

Constructors run automatically every time a new object of that class type is instantiated. In C++, destructors run when each individual object goes out of scope, not merely at the end of the entire program, and constructors can accept parameters.

A copy constructor in C++ takes a reference to an object of the same class. Declaration (3) 'C(C& t);' is the correct form - it accepts a reference to a C object. Declaration (2) 'C(C t);' creates a copy constructor that takes by value, which would cause infinite recursion (copying the argument requires calling the copy constructor), but C++ treats this as a valid declaration despite being problematic. The standard form is (3), and (2) is technically a copy constructor declaration though ill-formed.

A singleton class is a design pattern that restricts instantiation of a class to one object. This is achieved by making the constructor private, declaring a static instance variable, and providing a static public method (usually getInstance()) that returns the instance. Option C correctly states that a singleton can have only one object. Options A and B describe inheritance restrictions, which are not the definition of singleton.

Both malloc and new can allocate memory for any type, not just arrays or objects. In C++, new automatically initializes objects by invoking their constructors, whereas malloc simply allocates raw bytes of memory without performing initialization.

Pass by reference in C++ uses reference variables (using & in the parameter list) which act as aliases without explicit pointer dereferencing syntax, whereas pass by address passes pointer values that must be explicitly addressed and dereferenced. They are distinct concepts and mechanisms.