C++ Constants/ Literals

C++ Constants/ Literals: In C++ Constants/ Literals are nothing but they refer to fixed values. Their values cannot be changed once they are assigned. Constants can be of any of the basic data types. And these can be divided into integer numerals, floating point numerals, characters, boolean values, and strings.



C++ Constants/ Literals

  • Integer Literals
  • Floating Point Literals
  • Boolean Literals
  • Character Literals

Integer Literals

An integer literal can be octal, decimal (or) hexadecimal constant. And the integer literal can also have a suffix that is a combination of U and L for unsigned and long.  The suffix value can be in any order.

Examples:

85 //decimal
0213//octal
0x4b//hexadecimal
30 //int
30u //unsigned int
30l //long
30ul //unsigned long

Floating Point Literals

A floating point literal consists of an integer part, decimal point, fractional part, and an exponent part.  We can also represent them in decimal form (or) an exponential form.

If you are representing using the decimal form we must include the decimal point, exponent or both. And in case if you are representing an exponential form we should include the integer part (or) fractional part.

Example:

3.14159//Legal
314159E-5L//Legal
510E//Illegal: incomplete exponent
210f//Illegal: no decimal or exponent
.e55 /Illegal: missing integer or fraction

Boolean Literals

There two types of boolean literals present in C++. They are true and false. In this, we should not consider that the value of true is 1 and the value of false is 0.

Character Literals

These are enclosed in single quotes. And the literal letters begin with L  i.e. upper case only and wide character literal i.e L’x’ these should be stored in a simple variable of char type.

The character literal can be a plain character(i.e. ‘y’)  (or) an escape sequence (i.e. \’t’) or an universal character. (i.e.’\u02C0′).

Constant Definition in C++

In C++ they are different ways to define a constant. They are as follows:

  • Using const keyword
  • Using #define preprocessors

Constant Definition by Using const keyword

Syntax: const type constant_name;

Example:

#include <iostream>
using namespace std;
int main()
{
  const int SIDE = 50;
  int area;
  area = SIDE*SIDE;
  cout<<"The area of the square with side: " << SIDE <<" is: " << area << endl;
  system("PAUSE");
  return 0;
}

Output:

The area of the square with side: 50 is: 2500

Press any key to continue…

If you want we can place const keyword before (or) after

int const SIDE = 50;

 (or)

const int SIDE = 50;

Constant Definition by using #define preprocessor

Syntax: #define constant_name;

Example:

#include <iostream>
using namespace std;
#define VAL1 10   
#define VAL2  6
#define Newline '\n'
int main()
{
   int tot; 
   tot = VAL1 * VAL2;
   cout << tot;
   cout << Newline;
}

Output:

60