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Articles on Trending Technologies
Technical articles with clear explanations and examples
What are literals in C++?
A literal is any notation for representing a value within the source code. They just exist in your source code and do not have any reference a value in memory. Contrast this with identifiers, which refer to a value in memory.There are several types of literals in C++. Some of the examples of literals are −"Hello" (a string)3.141 (a float/double)true (a boolean)3 (an integer)'c' (a character)Things that are not literals −bar = 0; (a statement)3*5-4 (an expression)std::cin (an identifier)
Read MoreWhat is different between constant and variable in C++?
Variable and constant are two commonly used mathematical concepts. Simply put, a variable is a value that is changing or that have the ability to change. A constant is a value which remains unchanged.For example, if you have a program that has a list of 10 radii and you want to calculate the area for all of these circles. To find the area of these circles, you'll write a program that will have a variable that will store the value of PI and this value will not change throughout the program. Such values can be declared as a constant.In the ...
Read MoreWhat are different types of constants in C++?
There are no types of constants in C++. It's just that you can declare any data type in C++ to be a constant. If a variable is declared as constant using the const keyword, you cannot reassign its value. Example#include using namespace std; int main() { const int i = 5; // Now all of these operations are illegal and // will cause an error: i = 10; i *= 2; i++; i--; //... return 0; }
Read MoreHow to define constants in C++?
You can define constants in C++ by adding the const qualifier before the declaration of the variable. Example#include using namespace std; int main() { const int x = 9; x = 0; return 0; }This will define the constant variable x. But it will throw an error as we are trying to rewrite the value of a constant.
Read MoreHow to call an interface method in Java?
In order to call an interface method from a java program, the program must instantiate the interface implementation program. A method can then be called using the implementation object.Examplepublic interface InterfaceDemo{ default public void displayNameDefault(String name){ System.out.println("Your name is : " + name); } public void displayName(String name); public void displayNameAndDesignation(String name, String designation); }The above interface defines three methods for displaying a name and optionally a job title. One method is a default method that contains implementation logic. The remaining two methods do not include implementation logic.public class InterfaceDemoImpl ...
Read MoreWhat is type inference in C++?
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. In C++, the auto keyword(added in C++ 11) is used for automatic type deduction. 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 the ...
Read MoreHow can we get the list of MySQL server-side help categories?
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
Read MoreHow do we initialize a variable in C++?
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
Read MoreWhat does a semicolon do after a C++ class name?
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.
Read MoreWhat is the difference between prefix and postfix operators in C++?
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; ...
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