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C++ Basics Tutorial 5

C++ Basics Tutorial 5. Constants. Literal Constants Defined Constants Declared Constants. Topics Covered. Most easy to see and most obvious constants. Literal constants. Integer Numerals Floating-Point Numerals Boolean literals Character literals String literals.

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C++ Basics Tutorial 5

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  1. C++ Basics Tutorial 5 Constants

  2. Literal Constants • Defined Constants • Declared Constants Topics Covered

  3. Most easy to see and most obvious constants Literal constants

  4. Integer Numerals • Floating-Point Numerals • Boolean literals • Character literals • String literals Types of literal constants

  5. A number without decimal points (duh!) • Examples: 23, 56, 8… • In C++, expressing numerical constants does not require any special character like “”. • Integer numerals can be defined in other numeral forms like octal or hexadecimal. • 255 Decimal Value • 0377 Octal value • 0xff Hexadecimal Value All represent same number Integer Numerals

  6. To denote an octal number(Base 8 number) start the number with 0 (zero) • To denote a hexadecimal value(base 16 number) start with 0 x (zero “x”) • Write normally for decimal numerical(base 10) system value. • Force int to be unsigned by adding u(or U) at the end of number. (Ex: 19U) or l(or L) to make it long( 19L or 19UL) Decimal, Octal, hexadecimal, signed and unsigned representation

  7. To represent number with decimal or exponents • A decimal point “.” or a “e” can be added to represent the number, where e means to the “power by 10” to number after e. • Also can have both “e” and “.” • Example: 3.14 Value of Pi 5.97e24(Mass of earth) = 5.97 x 10 ^ 24 or 1.67e-27(Mass of proton) = 1.67 x 10 ^ -27 • Force number to be long double add L or l, to force number to be float add f or F in the end of the number • E or e both are same. C++ is not case sensitive in this case. Floating Point literals

  8. Only two boolean literals in C++: true or false. • Can be represented by bool data type. Boolean literals

  9. One character. Example: ‘a’, ‘b’, ‘A’ etc… • To represent character literals we put them inside single quotes. This is done to differentiate them from possible variable identifiers that we might define in the program. • If you just write 1 it is numerical literal. But ‘1’ makes it character literal. • ‘a’ is a character literal where as just a is a variable identifier named a. Character literals

  10. Combination of characters. • Inside double quotes “”. • Example “Dean” String literals

  11. Characters and string both can have a special character called escape character. • Impossible or at least difficult to express otherwise • Precede by a backslash(\) and a character. • Example: \n  New Line, \t  Tab • ‘\n’ or ‘\t’ or “LineOne\nLineTwo\nLineThree” • “\”DoubleQuote\”” = “DoubleQuote” when you print. Escape Characters

  12. \n  Newline • \t  tab • \r  carriage return • \v  vertical tab • \b  backspace • \f  form feed • \a  alert beep • \’  single quote(‘) • \”  Double quote(“) • \?  question mark(?) • \\  backslash(\) Few list of escape characters:

  13. Using something called preprocessor directive • Use #define preprocessor directive • Define constant that will be used frequently. • Example: #define PI 3.14159 #define NEWLINE ‘\n’ • This now have defined two constants called PI and NEWLINE. Now you can use PI and NEWLINE as other constants we learned earlier. • Due to #define the C++ compiler literally replaces all the occurrences of PI and NEWLINE with assigned value(3.14159 or ‘\n’) Defined constants

  14. A directive is not a C++ statement. It is interpreted by the preprocess that happens before even looking at the code of the program. So these directive does not need to have a semicolon in the end. • Directives start with #. Applies to #include as well. Directive

  15. Using const prefix with specific data type you make a variable unchangeable throughout the program. • Example: constint a = 23; const char newline = ‘\n’ • The are completely regular variables except that you cannot modify these after you initialize. Declared Constants (const)

  16. Next Chapter: We will talk about operators • Then: Basic input/ output. • End of Basics. • Then to Control structures / Functions Please Rate Comment and subscribe

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