Software languages

What is the difference between new and malloc?

Here are the differences between new and malloc, Operator new constructs an object (calls constructor of object), malloc does not. Hence new invokes the constructor (and delete invokes the destructor)This is the most important difference. operator new is an operator, malloc is a function. operator new can be overloaded, malloc cannot be overloaded. operator new […]

What is the use of new and delete operator in C++?

new operator is used to dynamically allocate memory on the heap. Memory allocated by new must be deallocated using delete operator. Syntax of new is: p_var = new type name; where p_var is a previously declared pointer of type typename. typename can be any basic data type. new can also create an array: p_var = […]

What is the use of extern in c/c++?

The extern keyword is used to tell the compiler that a data object is declared in a different *.cpp or *.c file. So there wont be any new memory is allocated for these variables. Check the below example and understand the working. //file1.cpp #include <iostream.h>   int x; extern void func2();   void func1(void) { […]

When we should use virtual destructor?

It is used whenever a base class pointer is pointing to its derived class. In such a case when a user tries to delete the base class pointer then it results in deallocating the memory occupied by the base class.Therefore instead the derived class getting destroyed the base class does. Now as the base class […]

How to allocate two dimensional array?

Consider if you want to allocate a two dimensional array: int a[10][3]; Then you have to allocate the rows first and then columns using for loops. Here is the C example code. int **a, x; //Allocate memory a = malloc(sizeof(int *) * 10); for(x = 0; x &lt; 10; x ++) { a[x] = malloc(sizeof(int) […]

How to run PHP files on localhost?

To run any php file you need to install Apache web server on your localhost. Also you need to install MySQL server for any database programming. You can install these separately or there is easy way to achieve the same by installing XAMPP. XAMPP is an easy to install Apache distribution containing MySQL, PHP and […]

What is PHP?

PHP stands for “Hypertext Preprocessor“,  is a server-side scripting language used to create dynamic Web pages. This can be embedded to HTML pages. This is very easy scripting language compare to other scripting languags. The goal of the language is to allow Web developers to write dynamically generated pages quickly. PHP supports many databases like […]