Constant in C++

by Monika Dadool 04-Sep-18

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Constant can be referred 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.
For 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"

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

1) Using #definepreprocessor.
2) Using constkeyword.
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

2) Using const keyword.

const prefix can be used to declare constants.

Syntax:

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

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