why i am getting error "unknown type name ‘PTR’ " ?

[Qt embedded developer]

when i am running below program code i am getting error :unknown type name ‘PTR’

#include <iostream>

typedef char* ptr;
#define char*  PTR

int main()
{
    ptr a,b;
    PTR A,B;
    
    cout<< sizeof(a);

    return 0;
}

I want to know how to resolve it ?

[J.Hilk]

@Qt-embedded-developer said in why i am getting error "unknown type name ‘PTR’ " ?:

#define char* PTR

#define PTR char*

[JonB]

@Qt-embedded-developer
Are you aware that your code illustrates an important rule about C/C++ type declaration statements, and that your ptr a,b is very different from PTR A,B?

typedef char* ptr;
ptr a,b;

declares both a & b to be of type char*.

However

#define PTR char*
PTR A,B;
// expands to:
char* A,B;
// but read as:
char *A, B;

In C/C++ this might look like it's equivalent to previous, but it is not. A is indeed of type char* but B is of type char --- no *. That's how C/C++ declarations work.

One moral: in modern C++ keep away from #defines for types, prefer typedef.