Numeric constants:       There are two types of numeric constants,
  1. Integer constants    
  2. Real or floating-point constants

Integer constants
  • Any whole number value is an integer.
  • An integer constant refers to a sequence of digits without a decimal point.
  • An integer preceded by a unary minus may be considered to represent a negative constant
    Example:            0          -33      32767

There are three types of integer constants namely,
                a)     Decimal integer constant                     
                b)     Octal integer constant
                c)     Hexadecimal integer constant                  

Decimal Integer constant (base 10)         
  • It consists of any combinations of digits taken from the set 0 through 9, preceded by an optional – or + sign.
  • The first digit must be other than 0.
  • Embedded spaces, commas, and non-digit characters are not permitted between digits.
    Valid:             0          32767     -9999          -23
    Invalid:
                        12,245            -   Illegal character (,)
                        10  20  30       -   Illegal character (blank space)

Octal Integer Constant (base 8)
  • It consists of any combinations of digits taken from the set 0 through 7.
  • If a constant contains two or more digits, the first digit must be 0.
  • In programming, octal numbers are used.
    Valid:                   037                 0          0435
    Invalid:
                            0786               -           Illegal digit 8
                            123                 -           Does not begin with zero
                            01.2                -           Illegal character (.)

Hexadecimal integer constant (base 16)
  • It consists of any combinations of digits taken from the set 0 through 7 andalso a through f (either uppercase or lowercase).
  • The letters a through f (or A through F) represent the decimal quantities 10 through 15 respectively.
  • This constant must begin with either 0x or 0X.
  • In programming, hexadecimal numbers are used.
    Valid Hexadecimal Integer Constant:            0x            0X1             0x7F           
    Invalid Hexadecimal Integer Constant:        
                                                                                0xefg  -           Illegal character g
                                                                                123     -           Does not begin with 0x

Unsigned integer constant:        An unsigned integer constant specifies only positive integer value. It is used only to count things. This constant can be identified by appending the letter u or U to the end of the constant. 

Valid:             0u          1U         65535u       0x233AU
Invalid:          -123      -         Only positive value

Long integer constant:     A long integer constant will automatically be generated simply by specifying a constant that exceeds the normal maximum value. It is used only to count things. This constant can be identified by appending the letter l or L to the end of the constant.          

Valid:             0l23456L       0x123456L    -123456l
Invalid:          0x1.2L            -           Illegal character (.)

Short integer constant:    A short integer constant specifies small integer value. This constant can be identified by appending the letter s or S to the end of the constant.

Valid:             123s                -456           32767S
Invalid:         
                        12,245                   -    Illegal character (,)
                        10  20  30  -   Illegal character (blank space)

Note: - A sign qualifier can be appended at the end of the constant. Usually suffixes(s or S, u or U, l or L) are not needed. The compiler automatically considers small integer constants to be of type short and large integer constants to be of type long.

Rules for constructing Integer constants 

i.               An integer constant must have at least one digit.
ii.              It must not have a decimal point.
iii.             It can be either positive or negative.
iv.             If no sign precedes an integer constant, it is assumed to be positive.
v.              Commas or blanks are not allowed within an integer constant.

Questions

Part-A
  1. What are the various types of Numeric constants?
  2. Define an integer? (Or) What is an integer?
  3. What is an integer constant?
  4. What are the various types of integer constants?
  5. Define integer constant and its types?
  6. Define decimal integer constant. Give examples?
  7. Define octal integer constant. Give examples?
  8. Define Hexadecimal integer constant. Give examples?
  9. State the rules for constructing Integer constants.
  10. Define unsigned integer constant. Give examples?
  11. Define long integer constant. Give examples?
  12. Define short integer constant. Give examples?
Part - B
  1. Write short notes on: Integer constants
  2. Explain about integer constants with examples?