typedef,#define

Question

Can anybody explain the difference between

#define int* char

and

typedef int* char;

Answer 1

There's no difference because both are illegal.

int* isn't a valid identifier for a macro, and even if you put a space in, neither is int, because it's a keyword and reserved. Even if you switched it to your likely intended #define char int*, it fails for the same reason.

And you cannot redefine the type char, so the typedef is a bust.

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The difference, had you given examples that were legal, is that #define is a preprocessing directive. It only does textual replacement, before the compiling stage. Contrarily typedef defines a new type, and that new type identifier respects "the rules" just like any other type.