C++ #define Vs typedef

#define	typedef
Is a preprocessor token: the compiler itself will never see it.	Is a compiler token: the preprocessor does not care about it.
Obeys scoping rules just like variables.	Stays valid until the end of the file (or until a matching undef).
Is a preprocessor directive used to define macros or general pattern substitutions. For eg. #define MAX 100, substitutes all occurrences of MAX with 100	Creates an "alias" to an existing data type. For e.g. typedef char chr;
#define INTPTR int* ... INTPTR a, b; After preprocessing, that line expands to int* a, b; Only a will have the type int *; b will be declared a plain int (because the * is associated with the declarator, not the type specifier).	typedef int *INTPTR; ... INTPTR a, b; In this case, both a and b will have type int *.