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In this article, we will learn about the p{ASCII} of the POSIX character class in Java regex. What is \p{ASCII}? In Java regex, \p{ASCII} POSIX character class matches any of the characters that fall within ASCII. ASCII (American Standard Code for Information Interchange) defines a character encoding standard consisting of 128 characters (0-127). This class matches the ASCII characters within the range of \x00-\x7F. Printable characters in the \p{ASCII} of the Java Regex are: Numbers (0 to 9) Uppercase letters (A to Z) Lowercase letters (a ... Read More
In Java, a HashMap is a subclass of the AbstractMap class and is used to store key-value pairs. Each key in the map is mapped to a single value in the map, and the keys are unique.Printing Java HashMap Elements We can insert a key only once in a map, and duplicate keys are not allowed, but the value can be mapped to multiple keys. We can add the elements using the put() method of the HashMap class and iterate over the elements using the Iterator interface. Java HashMap provides various ways to print its elements as follows: ... Read More
In this article we will check whether a double or floating point number is NaN (Not a Number) in C++. Checking if a Double or Floating Point Number is NaN To check, we can utilise the isnan() method. The isnan() function is available in the cmath library. This function was introduced in C++ version 11. So From C++11 next, we can use this function. The isnan() function is used to determine whether a double or floating point number is not-a-number (NaN) value. Return true if num is NaN, false otherwise. C++ Program to Check Double or Float Number is NaN ... Read More
What is an Assertions in C/C++? An assertion is a statement used to test assumptions made by the program. When an assertion fails, the program displays an error and stops. This is mainly used for debugging. In C and C++, assertions are handled using the assert() macro defined in the (C) or (C++) header file. Following is the declaration for assert() Macro. #include // in C // or #include in C++ assert(expression); The parameter of this assert() is expression: This can be a variable or any C/C++ expression. If ... Read More
In this article, we will see the differences between namespace and class in C++. Namespace and classes are two different concepts, so let's discuss them: Classes are datatypes. It is an expanded version of the structures. Classes can contain data members and functions as members, but namespaces can contain variables and functions by grouping them into one and cannot be created as objects; it is used as additional information to differentiate similar functions, classes, variables, etc. Variables, functions with the same name can be placed in different namespaces. What is Namespace? The namespace is a feature that provides a way ... Read More
What is Variadic Function In mathematics and in computer programming, a variadic function is a function of indefinite arity, i.e., a function that accepts a variable number of arguments. So, In C++ programming, we can say that a function that accepts a variable number of arguments is variadic function. Why Variadic Function Templates Are Used? In C++, templates can only have a fixed number of parameters, which must be specified at the time of declaration. However, variadic templates can help to solve this issue. Syntax to Create Variadic Function Following is the variadic function template syntax: template return_type function_name(arg var1, ... 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
In C or C++, we cannot return multiple values from a function directly. In this Article, we will see how to use some trick to return more than one value from a function. Returning Multiple Values from a Function We can return multiple values from a function by using the method. Below is the list of methods that are used to return multiple values from a function in C/C++: Using Pointers Using Structures Using Arrays Returning Multiple Values Using Pointers Pass the arguments by their addresses ... Read More
What is Conversion Operator Conversion operators are a type of operator overloading in C++. These operators are commonly known as type-cast operators. They enable a class or structure to specify how an object should be converted into another data type. Sometimes we need to convert concrete-type objects to some other type of objects or primitive data types. To make this conversion we can use a conversion operator. Following is the syntax to use the conversion: class ClassName { public: operator TargetType() const { // conversion logic } }; ... Read More
In C++, we allocate the memory dynamically using the new operator. But there is a special version of this operator known as placement new operator. The new operator performs two things. It allocates memory, and then constructs an object in allocated memory. But for the placement new operator, it constructs object at the given address. What is Placement New? The placement new operator allows you to construct an object at a specific memory location. Its syntax lets you place an object at a pre-allocated memory address instead of letting the compiler allocate memory. new (address) Type (constructor_args); Where ... Read More