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In C++, declaration and definition are often confused. A declaration means (in C) that you are telling the compiler about type, size and in case of function declaration, type and size of its parameters of any variable, or user-defined type or function in your program. No space is reserved in memory for any variable in case of a declaration.The Definition on the other hand means that in additions to all the things that declaration does, space is additionally reserved in memory. You can say "DEFINITION = DECLARATION + SPACE RESERVATION".Following are examples of declarations −extern int a; ... Read More
Oracle has released Java 9 version with a rich set of new features and brings a lot of new enhancements.Below are a few important features and enhancements introduced in Java 9.Factory Methods for Collections: Factory methods are special kinds of static methods that can be used to create unmodifiable instances of collections, which means we can use these methods to create a list, set, and map.Java Platform Module System (JPMS): A Java Module is a mechanism to bundle java applications and java packages into a Java module. It specifies which of the java packages that contain visible to other java modules by using ... Read More
We can get the list of MySQL server-side help categories by giving the keyword contents to the help command.mysql> help contents You asked for help about help category: "Contents" For more information, type 'help ', where is one of the following categories: Account Management Administration Compound Statements Data Definition Data Manipulation Data Types Functions Functions and Modifiers for Use with GROUP BY Geographic Features Help Metadata Language Structure Plugins Procedures Storage Engines Table Maintenance Transactions User-Defined Functions Utility
Auto is a keyword in C++11 and later that is used for automatic type deduction. Type inference or deduction refers to the automatic detection of the data type of an expression in a programming language. It is a feature present in some strongly statically typed languages. For example, you want to create an iterator to iterate over a vector, you can simply use auto for that purpose. example#include #include using namespace std; int main() { vector arr(10); for(auto it = arr.begin(); it != arr.end(); it ++) { cin >> *it; } return 0; }In ... Read More
You can initialize a variable using the assignment operator or use its constructor when initializing it. For example,int i = 0; MyClass instance(1, "Hello");It will be automatically initialized ifIt's a class/struct instance in which the default constructor initializes all primitive types; like MyClass instance; You use array initializer syntax, e.g. int a[10] = {} (all zeroed) or int a[10] = {1,2}; (all zeroed except the first two items: a[0] == 1 and a[1] == 2) It is a global/extern variable It is defined static
If you have statements like −Class Person;This is a forward declaration. It lets the following code know that there is are classes with the name Person. This satisfies the compiler when it sees these names used. Later the linker will find the definition of the classes.
Yes, we can declare the main method as private in Java.It compiles successfully without any errors but at the runtime, it says that the main method is not public.Example:class PrivateMainMethod { private static void main(String args[]){ System.out.println("Welcome to Tutorials Point"); } }The above code is working successfully at compile time but it will throw an error at the runtime.Output:Error: Main method not found in class PrivateMainMethod, please define the main method as: public static void main(String[] args) or a JavaFX application class must extend javafx.application.Application
An enumerated type declares an optional type name and a set of zero or more identifiers that can be used as values of the type. Each enumerator is a constant whose type is the enumeration. For example, if you are creating an application that has a fixed number of types for some variable. For example, let's say gender, it can be of three types male, female and others. You can define and use an enum like −#include using namespace std; enum Gender {MALE, FEMALE, OTHERS}; int main() { Gender gen = Gender.FEMALE; return 0; }By default, the value ... Read More
The equality operators in C++ are is equal to(==) and is not equal to(!=). They do the task as they are named. The binary equality operators compare their operands for strict equality or inequality. The equality operators, equal to (==) and not equal to (!=), have lower precedence than the relational operators, but they behave similarly. The result type for these operators is bool.The equal-to operator (==) returns true (1) if both operands have the same value; otherwise, it returns false (0). The not-equal-to operator (!=) returns true if the operands do not have the same value; otherwise, it returns ... Read More
In the prefix version (i.e., ++i), the value of i is incremented, and the value of the expression is the new value of i. So basically it first increments then assigns a value to the expression. In the postfix version (i.e., i++), the value of i is incremented, however, the {value|the worth} of the expression is that the original value of i. So basically it first assigns a value to expression and then increments the variable.Let's look at some code to get a better understanding −Example#include using namespace std; int main() { int x = 3, y, z; ... Read More