5. Introduction to c++: Constants: Basic Programming for Beginners :: Videos
Description:
Topics Covered Here:
- Literal Constants
- Defined Constants
- Declared Constants
- Literal constants
Most easy to see and most obvious constants: Literal Constants.
Types of literal constants:
- Integer Numerals:
- 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
- Decimal, Octal, hexadecimal, signed and unsigned representation
- 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)
- Floating-Point Numerals:
- 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 "." Examples:
- 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.
- Boolean literals:
- Only two boolean literals in C++: true or false.
- Can be represented by bool data type.
- Character literals:
- Represents only 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 a numerical literal. But '1' makes it character literal.
- 'a' is a character literal where as just a is a variable identifier named a.
- String literals:
- Combination of characters.
- Inside double quotes (" ").
- Example "Dean"
- Escape Characters
- Characters and string both can have a special character called escape character.
- Characters that are impossible or at least difficult to express otherwise
- Precede by a backslash(\) and the character.
- Examples:
- \n (New Line),
- \t (Tab)
- '\n' or '\t' or
- "LineOne\nLineTwo\nLineThree"
- "\"DoubleQuote\"" = "DoubleQuote" when you print.
- Few list of escape characters:
- \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(\) Defined constants
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