Programming Articles - Page 2714 of 3366

In C/C++ we can use octal literals by typing a zero before the actual number. For example, if an octal number is 25, then we have to write 025.Example Code#include int main() {    int a = 025;    int b = 063;    printf("Decimal of 25(Octal) is %d", a);    printf("Decimal of 63(Octal) is %d", b); }OutputDecimal of 25(Octal) is 21 Decimal of 63(Octal) is 51

Yes, C++ virtual functions can have default parameters. The default parameter is the value provided during function declaration, such that the value can be automatically assigned if no argument is passed to them. In case any value is passed the default value is overridden and becomes a parameterized argument. Virtual Function A virtual function is a member function declared in a base class and can be overridden in a derived class. When we use a pointer or reference to the base class to refer to an object of the derived class, you can call a virtual function for that object. ... Read More

In this section, you will learn how to use SQLite in C/C++ programs.InstallationBefore you start using SQLite in our C/C++ programs, you need to make sure that you have SQLite library set up on the machine. You can check SQLite Installation chapter to understand the installation process.C/C++ Interface APIsFollowing are important C/C++ SQLite interface routines, which can suffice your requirement to work with SQLite database from your C/C++ program. If you are looking for a more sophisticated application, then you can look into SQLite official documentation.Serial NoAPI & Description1sqlite3_open(const char *filename, sqlite3 **ppDb)This routine opens a connection to an SQLite ... Read More

Virtual functions calling from a constructor or destructor is dangerous and should be avoided whenever possible as the virtual function we call is called from the Base class and not from the derived class.The reason is that in C++ Super-classes are constructed before derived classes. So, in the following example, as B must be instantiated, before D is instantiated. When B's constructor is called, it's not D yet, so the virtual function table still has the entry for B's copy of s().Example Code Live Demo#include using namespace std; class B {    public: B() {       s();    } ... Read More

In this section we will see how to execute zombie process and orphan process in a single program in C/C++. Before going to the main discussion, let us see what are the zombie process and orphan process.Zombie ProcessesA zombie process is a process whose execution is completed but it still has an entry in the process table. Zombie processes usually occur for child processes, as the parent process still needs to read its child’s exit status. Once this is done using the wait system call, the zombie process is eliminated from the process table. This is known as reaping the ... Read More

In this section, you will learn how to use SQLite in C/C++ programs.InstallationBefore you start using SQLite in our C/C++ programs, you need to make sure that you have SQLite library set up on the machine. You can check the SQLite Installation chapter to understand the installation process.C/C++ Interface APIsFollowing are important C/C++ SQLite interface routines, which can suffice your requirement to work with SQLite database from your C/C++ program. If you are looking for a more sophisticated application, then you can look into SQLite official documentation.Serial NoAPI & Description1sqlite3_open(const char *filename, sqlite3 **ppDb)This routine opens a connection to an ... Read More

In C++, virtual and pure virtual functions are key features supporting polymorphism both allow different classes to respond uniquely to the same function call. What is Virtual Function A virtual function in C++ is a member function in a base class, which allows a function to be overridden in the derived class. This process helps in enabling runtime polymorphism. A virtual function is declared in the base class using the virtual keyword. Syntax Following is the syntax of the virtual function: class BaseClassName { public: virtual void func_name() { // implementation ... Read More

An lvalue (locator value) represents an object that occupies some identifiable location in memory (i.e. has an address).rvalues are defined by exclusion. Every expression is either an lvalue or an rvalue, so, an rvalue is an expression that does not represent an object occupying some identifiable location in memory.For example, An assignment expects an lvalue as its left operand, so the following is valid:int i = 10; But this is not: int i; 10 = i;This is because i has an address in memory and is a lvalue. While 10 doesn't have an identifiable memory location and hence is an ... Read More

A pure virtual function is a function that has no implementation in the base class and must be overridden by any derived class. It is declared using = 0 in the base class. Pure Virtual Destructor When we want the base class to be abstract then we declare a pure virtual Destructor. A pure virtual Destructor can be declared in C++ after a destructor has been created as a pure virtual object. One of the most important things is that if a class contains a pure virtual destructor, it must provide a function body for the pure virtual destructor. ... Read More

In this section we will see what is the fork system call in C. This fork system call is used to create a new process. This newly created process is known as child process. The current process which is creating another child process is called the parent process.A child process uses the same program counter, CPU register, same files that are used by the parent process.The fork() does not take any parameter, it returns integer values. It may return three types of integer values.Negative Number: It returns negative number when child process creation is failedZero Value: It returns Zero for ... Read More