Variables and constants in C++

In C++, variables and constants are used to store and represent different values in a program. Here is a brief overview of variables and constants in C++:

Variables:
– A variable is a named storage location in memory that holds a value of a particular data type.
– The value of a variable can be changed during program execution.
– To create a variable in C++, you need to specify its data type and name. For example, `int x = 42;` creates an integer variable named x and assigns it the value 42.
– The value of a variable can be updated using the assignment operator (=). For example, `x = 10;` assigns the value 10 to the variable x.

Constants:
– A constant is a named value that cannot be changed during program execution.
– Constants are often used to represent values that are fixed or do not change.
– To create a constant in C++, you need to use the const keyword and specify its data type and name. For example, `const double PI = 3.14;` creates a constant named PI and assigns it the value 3.14.
– You cannot change the value of a constant during program execution. Attempting to do so will result in a compiler error.

Variables and constants can be used in expressions and calculations within a program. For example, you can perform arithmetic operations on variables and constants:

int x = 10;
int y = 5;
int z = x +y; // z is now 15

const double GRAVITY = 9.81;
double mass = 10.0;
double weight = mass * GRAVITY; // weight is now 98.1

In addition to the basic data types and constants, C++ also supports user-defined data types, such as structures and classes, which can be used to create more complex data structures and objects.