Add prefix to a macro that calls printf - c

Question

Having this #define PRINTF(...) printf(__VA_ARGS__) I want to create a macro that calls PRINTF but that adds prefix to the printed string, for example:
#define PRINTF_P(<args>) PRINTF(<whatever>)
// let's suppose that the desired prefix is 'prefix - '
PRINTF_P("Hello world\n");
PRINTF_P("Hello world, num = %d\n", 25);
// Result:
prefix - Hello world
prefix - Hello world, num = 20
How can I do this?
What I have tried
The following works for calls like PRINTF_P("string with argument %d\n", arg), but it doesn't for calls like `PRINTF_P("string with no argument\n");
#include <stdio.h>
#include <stdarg.h>
#define PRINTF(...) printf(__VA_ARGS__)
#define A(fmt, ...) fmt
#define B(fmt, ...) __VA_ARGS__
#define PRINTF_P(...) printf( "prefix - " A(__VA_ARGS__), B(__VA_ARGS__))
int main(void)
{
PRINTF_P("No number\n"); // This fails
PRINTF_P("Number = %d\n", 20); // This works
return 0;
}
EDIT
I'm referring only to the case of string literals, not char *.

Answer 1

It is as easy as:
#include <stdio.h>
#include <stdarg.h>
#define PRINTF(...) printf(__VA_ARGS__)
#define PRINTF_P(...) printf( "prefix " __VA_ARGS__)
int main(void)
{
PRINTF("No number\n");
PRINTF("Number = %d\n", 20);
PRINTF_P("No number\n");
PRINTF_P("Number = %d\n", 20);
return 0;
}

Answer 2

I'm not sure why you should use a macro at all.
Just write an encapsulating function using vprintf and variable args.
IDEOne Link
#include <stdarg.h>
int prefix_printf(const char* fmt, ...)
{
printf("prefix "); // Print desired Prefix
va_list args; // Declare a variable for the "..."
va_start(args, fmt); // Initialize the args as everything after parameter "fmt"
int result = vprintf(fmt, args); // Variant of printf that accepts args instead of ...
va_end(args); // Clean up the args
return result; // Return the same value printf would've returned
}
int main(void) {
prefix_printf("No number\n");
prefix_printf("Number = %d\n", 20);
return 0;
}
Result:
Success #stdin #stdout 0.01s 5536KB
prefix No number
prefix Number = 20