C++ Constants/Literals

Constants refer to fixed values that the program may not alter and they are called pterals.

Constants can be of any of the basic data types and can be spanided into Integer Numerals, Floating-Point Numerals, Characters, Strings and Boolean Values.

Again, constants are treated just pke regular variables except that their values cannot be modified after their definition.

Integer Literals

An integer pteral can be a decimal, octal, or hexadecimal constant. A prefix specifies the base or radix: 0x or 0X for hexadecimal, 0 for octal, and nothing for decimal.

An integer pteral can also have a suffix that is a combination of U and L, for unsigned and long, respectively. The suffix can be uppercase or lowercase and can be in any order.

Here are some examples of integer pterals −

212         // Legal
215u        // Legal
0xFeeL      // Legal
078         // Illegal: 8 is not an octal digit
032UU       // Illegal: cannot repeat a suffix

Following are other examples of various types of Integer pterals −

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

Floating-point Literals

A floating-point pteral has an integer part, a decimal point, a fractional part, and an exponent part. You can represent floating point pterals either in decimal form or exponential form.

While representing using decimal form, you must include the decimal point, the exponent, or both and while representing using exponential form, you must include the integer part, the fractional part, or both. The signed exponent is introduced by e or E.

Here are some examples of floating-point pterals −

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 are two Boolean pterals and they are part of standard C++ keywords −

A value of true representing true.

A value of false representing false.

You should not consider the value of true equal to 1 and value of false equal to 0.

Character Literals

Character pterals are enclosed in single quotes. If the pteral begins with L (uppercase only), it is a wide character pteral (e.g., L x ) and should be stored in wchar_t type of variable . Otherwise, it is a narrow character pteral (e.g., x ) and can be stored in a simple variable of char type.

A character pteral can be a plain character (e.g., x ), an escape sequence (e.g., ), or a universal character (e.g., u02C0 ).

There are certain characters in C++ when they are preceded by a backslash they will have special meaning and they are used to represent pke newpne ( ) or tab ( ). Here, you have a pst of some of such escape sequence codes −

Following is the example to show a few escape sequence characters −

#include <iostream>
using namespace std;

int main() {
   cout << "Hello	World

";
   return 0;
}

Hello   World

"hello, dear"

"hello, 

dear"

"hello, " "d" "ear"

#define identifier value

#include <iostream>
using namespace std;

#define LENGTH 10   
#define WIDTH  5
#define NEWLINE  
 

int main() {
   int area;  
   
   area = LENGTH * WIDTH;
   cout << area;
   cout << NEWLINE;
   return 0;
}

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const type variable = value;

#include <iostream>
using namespace std;

int main() {
   const int  LENGTH = 10;
   const int  WIDTH  = 5;
   const char NEWLINE =  
 ;
   int area;  
   
   area = LENGTH * WIDTH;
   cout << area;
   cout << NEWLINE;
   return 0;
}

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