const_#define_typedef_enum

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               /***	CONSTANT KEYWORD	***/
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* It tells the compiler that this value cannot be changed.

* const int i =5;
  i++; // Error : compilation 

*Type checking is performed in constant whereas not performed in #define[PRE_PROCESSING].
  ex : #define MYVALUE '5.0'
       int i = MYVALUE;

	while preprocessing it will substitute the value without type-checking.

* const variables are separetly stored in "READ_ONLY SECTION".

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             /***	TYPEDEF KEYWORD		***/
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* It is used to create new data types, or assign a new name to exiting data types.

* syntax: typedef <data_type> <new data_type>

* example: typedef unsigned char BYTE;

* 	int main()
	{
		BYTE ch1, ch2;
		ch1 = 10, ch2 = 20;
		printf("ch1 is %d/t ch2 is %d\n",ch1,ch2);
		return 0;
  	}

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			   /***	TYPEDEF 	    VS 	 #DEFINE	***/
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		-compilation stage			  -preprocessing stage
		-new name/another name to data_type       -Data types,Variables
		-typedef unsigned char *PTR;		  -#define unsigned char* PTR
		    PTR a,b,c;					PTR a, b, c;
		    => unsigned char *a, b, c;           	=> unsigned char* a, b, c;

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			/*** 	ENUMS 	***/
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*enum is used to create new data type.

*enum is used only for integer constants.

*enum is used to create user-defined data types.

*sizeof(enum) == sizeof(integer)

*Addition, Substraction on enum values can be possible.

*You can assign integer value to it.

*scope rule in enum not in #define

*You can assign same values to members in enum.
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