constants in c programming

-

Constants: -

  • A constant is a value that cannot be changed during the execution of the program.
  • It is fixed, and once defined, its value cannot be modified by the program.
  • A constant can be a number, a character, or a string.
  • Constants are used to store values that must stay the same throughout the program.
  • We can use constants for values like integers, floating-point numbers, characters, or enumeration values.
  • A constant can belong to any data type, like int, float, or char.


Syntax:

                    const data_type variable_name; (or) const data_type *variable_name;


Types of C constants:  C constants are mainly classified into two categories:

            1. Primary Constants

            2. Symbolic Constants

 

1) Primary Constants: - The primary constants are:

                a. Integer constants.

                b. Real or Floating-point constants.

                c. Character constants.

                d. String constants.

                e. Escape sequence constants.

 

a) Integer constants: -

  • The integer constants are whole numbers without any decimal point.
  • An integer constant must have at least one digit.
  • It can be positive or negative.
  • An integer 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 can also have a suffix that is a combination of 'U' for unsigned and 'L' for long.
  • No commas or blanks are allowed within an integer constant.

 

                Examples: 100, -45, 0

 

                There are three types:

                                                                Decimal (Base 10): e.g., 123

                                                                Octal (Base 8): Starts with 0, e.g., 076

                                                                Hexadecimal (Base 16): Starts with 0x, e.g., 0x7F

 

b) Real or Floating-point constants: -

  • These are numbers with decimal points or in exponential form.
  • A real constant must have at least one digit.
  • It must have a decimal point.
  • A floating-point literal has an integer part, a decimal point, a fractional part, and an exponent part.

 

        Examples: 3.14, -0.001, 2.5e3 (which means 2.5 × 10³ = 2500)

        Note: E-5 = 10-5

 

c) Character constants: -

  • A character constant represents a single character enclosed in single quotes.
  • The maximum length of a character constant is 1 character.

 

                Examples: 'A', '1', '%'

 

d) String constants: -

  • A string constant is a sequence of characters enclosed in double quotes.
  • Unlimited length can allow any number of characters.

 

            Examples: "Hello", "123", "C Language"

 

e) Escape sequence constants: -

  • There are some characters which have special meaning iin the Clanguage.
  • They should be preceded by a backslash symbol to make use of their special function.
  • The list of special characters and their purpose.

 

Backslash_character

Meaning

\b

Backspace

\f

Form feed

\n

New line

\r

Carriage return

\t

Horizontal tab

\”

Double quote

\’

Single quote

\\

Backslash

\v

Vertical tab

\a

Alert or bell

\?

Question mark

\N

Octal constant (N is an octal constant)

\XN

Hexadecimal constant (N – hex.dcml cnst)

 

2) Symbolic Constants: -

  • Symbolic constants are constants that are named using #define or const keyword.


using #define :

            #define PI 3.14159,  Here, PI is a symbolic constant, and its value cannot be changed.

 

            Examples     

                                        #define LENGTH 10  

                                        #define WIDTH  5

                                        #define NEWLINE '\n'

 

 Using const:

        const int MAX = 100;  Here, MAX is a constant integer that holds the value 100.

 

            Examples     

                                        const int  LENGTH = 10;

                                        const int  WIDTH = 5;

                                        const char NEWLINE = '\n';

 

Popular posts from this blog

operators in c programming

-
Image
v Operators: - An operator is a symbol that tells or intimates to the compiler to perform specific calculations or manipulations on one or more operands. Operators are essential for performing computations and making decisions in programs.   a + b is an operation a & b are operands + is an operator   Based on number of operands involved: 1.      Unary operators: - unary operators can be applied on only one operator. Example: -   ++ , -- , - (unary minus) , sizeof , ~ (compliment) , ! (not).   2.      Binary operators: - binary operators can be applied on two operands. Example: -   + , -,   * , / , etc.   3.    Ternary operators: - Ternary operator can be applied on three operands. Example: -   ?: (ternary conditional operator).   C supports several operators, can be classified into following...
Read more

Variables in c

-
Image
  Variables: - A variable is a data name or an identifier which stores a value that can be changed during the program execution.  Every variable might belong to any of the data types, like int, float, char, etc.  The name of a variable can be composed of letters, digits, and the underscore character. It must begin with either a letter or an underscore.  Variables are case-sensitive because uppercase and lowercase letters are distinct. C programming language also allows defining various other types of variables, like numeric array, character array, pointer, Structure, Union, Enumeration and etc.               Example: - sum, height, _value Declaring a variable in C: - Variable declaration means telling the compiler about the name and type of a variable before using it in the program. Variable declaration is the process of reserving a memory location and defining the type of data that will be stored in that locatio...
Read more

Cloud Storage and Local Storage: Applications in Business

-
  Cloud Storage and  Local Storage: Applications in Business: -   Local Storage: - Local storage refers to storing data such as text, audio, video, graphics, animation, special characters, constants, mathematical expressions and numeric data on physical devices in our computer or other electronic devices. Local storage in business refers to storing business data such as customer contact information, sales records, financial statements, employee data, market research, operational metrics, raw information like customer feedback.  It can also stores the structured data, such as in spreadsheets, or unstructured, like text from surveys or social media post on physical devices like hard drives, SSDs, or company servers within the organization’s premises.  The business owns and manages the storage hardware.  Local storage provides faster access to large files, which is helpful for tasks like video editing, 3D rendering, and engineering design projects. It o...
Read more