Constant in C++

Constant can be referred to as an entity that doesn't change throughout the program.

There are different types of constant available in C++ i.e. integer constant (whole number), floating-point constant (number with decimal values), a character constant.

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Example:

Integer Constant = 37, 45

Floating Point Constant = 46.7, 57.8

Character Constant = This type of constant is written in single quotes i.e. 'a', 'b'

String Constant = This type of constant is written in double-quotes i.e. "Anita", "Anmol"

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In C++, There are two simpler techniques can be used to define constants.

1. Using #definepreprocessor
2. Using the const keyword
3. #definepreprocessor

Syntax: #define identifier value

Example:

#include <iostream>
using namespace std;
#define LENGTH 4 
#define WIDTH  8
#define NEWLINE '\n'
int main() {
   int area; 
   area = LENGTH * WIDTH;
   cout << area;
   cout << NEWLINE;
   return 0;
}

Result:

32

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2) Using the const keyword

The const prefix can be used to declare constants.

Syntax:

const type variable = value;
const int size = 4;