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Constants and variables in c programming
Constants are values that do not change during program execution and include numeric constants like integers and floating point numbers, as well as string or character constants. Variables are identifiers that are used to refer to values that can change during program execution. Common variable types in C include integers, floating point numbers, characters, and strings. Variables must be declared with a data type before being assigned values and have naming conventions like starting with a letter and being less than 32 characters.
Constants and variables in c programming
- 1. Constants and Variablesin C programming Chitrank Dixit
- 2. Constants Any unchanged valuein a program during the program execution is called constant. Following are the constants in C language. • Numeric Constants • String or Character Constants.
- 3. Numeric Constants • IntegerConstant – An integer constant is a signed or unsigned whole number. – Example: -23 +356 46 – C language supports an integer constant in octal (base 8) , decimal (base 10) and hexadecimal (base 16). The default number system followed in C language is decimal (base 10). – An octal number is preceded by zero (0) and a hexadecimal number is preceded by 0x or 0X.
- 4. • Real orfloating point constant: – Any signed or unsigned number with fractional part is called real or floating point constant. A real constant can be written in decimal or exponential form. – Example – Decimal Form 0.254 +342.0 - 3.15 – Exponential Form 0.218e6 0.42e-32 - 1.0e12 – (0.218e6 means --> 0.218 x 10^6 and so on for all)
- 5. String or CharacterConstants • Any string of characters enclosed in apostrophes or quotes is called string constant or character constant. There are two types of string constants. • Single Character String Constant • String of Characters Constant
- 6. Single Character StringConstant • Any letter or character enclosed in single apostrophe is called single character string constant. – Example: 'y' '$' '+'
- 7. String of CharactersConstant • Any string of characters consisting of letters, digits and symbols enclosed in double quotes is called string of characters constant. – Example: – "Total value is“ , “12 vyas fala”, “value is = “
- 8. Variables • A variableis an identifier or a name which is used to refer a value and this value varies or changes during the program execution. A variable is written with a combination of letters , numbers and special characters _(underscore) with the first letter being an alphabet. Maximum of 31 letters can be used to write a variable. – Example: x , fact , c22 , total_value
- 9. Important rules whilewriting a variable in C Programming • Upper and Lower case alphabets are taken differently, so the variables SUM and sum are referring to different values. • No special characters other than underscore ( _ ) are permitted. • Some C compilers will not accept more than 8 characters. So it is a good practice writing a variable with few letters which makes it also convenient to write and use • All variables used in a C program are declared with appropriate data types before the variable is assigned any value. • Reserved words cannot be used as variables.