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This video related to this article basically introduces what are the variables and variable identifiers in C++, how are they used and why are they important and also how to use them to make a program more useful.

Key terms:

• Variable: Portion of memory to store and determine a certain value. 
• Valid identifier: sequence of letters, numbers and underscore, and cannot start with number. Can start with underscore(_) but not recommended.
• Reserved keywords: That are there already for compiler to use and we declaring them will just try to initialize again causing error.
• List of reserved keywords:

  asm, auto, bool, break, case, catch, char, class, const, 
  const_cast, continue, default, delete, do, double, 
  dynamic_cast, else, enum, explicit, export, extern, 
  false, float, for, friend, goto, if, inline, int, long, 
  mutable, namespace, new, operator, private, protected, 
  public, register, reinterpret_cast, return, short, 
  signed, sizeof, static, static_cast, struct, switch, 
  template, this, throw, true, try, typedef, typeid, 
  typename, union, unsigned, using, virtual, void, 
  volatile, wchar_t, while 

• Operator words that may be reserved:

  and, and_eq, bitand, bitor, compl, not, not_eq, or, 
  or_eq, xor, xor_eq

• List of fundamental data type:

Type	size	Range
char	1 byte	signed: -128 to 127 unsigned: 0 to 255
short int (short)	2 bytes	signed: -32768 to 32767 unsigned: 0 to 65535
int	4 bytes	signed: -2147483648 to 2147483647 unsigned: 0 to 4294967295
long int (long)	4 bytes	signed: -2147483648 to 2147483647 unsigned: 0 to 4294967295
bool	1 byte	true or false
float	4 bytes	+/- 3.4e +/- 38 (~7 digits)
double	8 bytes	+/- 1.7e +/- 308 (~15 digits)
long double	8 bytes	+/- 1.7e +/- 308 (~15 digits)
wchar_t	2/4 bytes	1 wide character

 

• Variables can be initialized basically in two ways:
  • int a = 10; or
  • int a (10);
• string variable types can store bunch of characters.

 

• Resources: Download notepad++ here

Other Articles:

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