Constants & Literals in C++

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

Now let's see these in details.

Integer Literals:

Integer literals are used for the storage of the integer values. There are two ways of representation of integer literals

• Prefix style
• Suffix style

• Prefix Style: Prefix style generally specifies the base of the integer. There are mainly four types of the prefix representation style.
  
  • Decimal or Base 10: In this representation the first digit should be a non-zero decimal digit and then followed by zero more decimal digits.
    Ex. 25, 8, 16, 500, etc.
  • Hexa-Decimal or Base 16:In this representation we first have to mention "0x" or "0X" and then followed by one or more hexa-decimal digits from
    0 to f.
    Hexa-Decimal digits - 0,1,2,3,4,5,6,7,8,9,a,b,c,d,e and f.
    Ex. 0x52, 0x5c, 0X85ac4, 0xface,0Xdead, etc.
  • Octal or Base 8: This representation starts with "0" and then followed by one or more octal digits form 0 to 7.
    Octal digits - 0,1,2,3,4,5,6,7
    Ex. 05410, 025, 010, etc.
  • Binary or Base 2: This representation starts with "0b" or "0B" and then followed by one or more binary digits 0 or 1.
    Ex. 0b0110, 0b111101101, 0B0101, etc.
• Suffix Style: In suffix style, depending on the size or charactersitics of the integer type we add the symbol at the end of the decimal.
  Ex. 105l, 55ul, 66u, etc.
  Suffix representation depending on the datatypes is as follow:

  Data Type	Suffix	Example
  Integer	No suffix required	const int value = 50
  Long Integer	l or L	const long int value = 50L
  Long Long Integer	ll or LL	const long long int value = 235LL
  Unsigned Integer	u or U	const unsigned int value = 4545U
  Unsigned Long Integer	ul or UL	const unsigned long int value = 5555442245UL
  Unsigned Long Long Integer	ull or ULL	const unsigned long long int value = 50505050505050ULL

Floating Point Literals:

Floating point literals are used for the storage of the real value values. Floating point literals consist of integre part, real part, fractional part
and exponential part.It can be represented by two types:

• In Decimal form: In this style of representation we have to give a decimal point or exponent part or both of them.
  Ex. 105.568, 88558.86868 etc
• In Exponential form: In this style of representation we have to give integer part or fractional part or both of them.
  Ex. 1.05568e+2, 8.855886868e+4 etc

String Literals:

String literals are used to store the sequence or group of characters or we can say a word. It will also allow to store the special character and
escape sequences. In the representation the value should be given inside the double quotes.
Ex. const string value = "Hello!";
      const string value = "The Geeky Core!";

Character Literals:

Character literals are used to store a single character. This should be stored inside the single quotes.
Ex. const char value = 'A';
Also, declaring multiple characters inside a single quote will give the warning of 'multi-character constant' and prints only the last character.
For example if we write const char value = 'AB', them it will first give the warning and prints only character 'B'. So to hold multiple characters,
we should either use the string literals as described above or use the character array and double-quotes instead.
Ex. const char value[] = "ABCD";
We can also use the character literals to store the escape sequences. Some of the escape sequences we can find in C++ are as below:

A simple code example to describe String and Character literals:-

              
                #include < iostream>
                  using namespace std;
                  
                  int main() 
                  { 
                    const char value1 = 'A';
                    const char value2[] = "ABCD";
                    const string value3 = "Hello!";
                    const string value4 = "The\tGeeky\tCore";
                    const string value5 = "Entering\ninto\nthe\nnewline.";
                    const string value6 = "I want to say, \"Happy Coding..\"";
                      
                      cout << value1<< endl; 
                      cout << value2<< endl; 
                      cout << value3<< endl; 
                      cout << value4<< endl; 
                      cout << value5<< endl; 
                      cout << value6;
                      return 0; 
                  } 
              
            

The output will be:

              
                A
                ABCD
                Hello!
                The	Geeky	Core
                Entering
                into
                the
                newline.
                I want to say, "Happy Coding.."
              
            

The above code will explain the usage and syntax of string and character literals.

Boolean Literals:

Boolean literals generally used to store or represent boolean datatype. It mainly store two values:

• True: The keyword used here is "true" and stored value will equals to 1.
• False: The keyword used here is "false" and stored value will equals to 0.

Ex. const bool value = "true"