Using #define to include Serial.printf() or not

Projects Programming
1

I'm using Ralph Bacons YouTube video that explains how to incorporate Serial.printf() or not.
This works very well and I've increased the number of #define required in order to select the correct Serial.printf().

The code is as follows:

#define DEBUG1  0       // if 0 then DEBUG(n) does not display, if 1 then it does
#define DEBUG2  0
#define DEBUG3  0
#define DEBUG4  0 

#if DEBUG1 == 1
#define debug1(a)    Serial.printf(a)
#else
#define debug1(a) 
#endif

#if DEBUG2 == 1
#define debug2(a,b)    Serial.printf(a,b)
#else
#define debug2(a,b) 
#endif

#if DEBUG3 == 1
#define debug3(a,b,c)  Serial.printf(a,b,c)
#else 
#define debug3(a,b,c) 
#endif

#if DEBUG4 == 1
#define debug4(a,b,c,d)  Serial.printf(a,b,c,d)
#else 
#define debug4(a,b,c,d) 
#endif

so in the code you use debug1(), debug2(), debug3() and debug(4).
Whilst this works fine I was thinking if there was a way to determine which debug(n) was required so you could just use debug() and the # code would be simpler.

2

You could use a macro with variadic arguments that replaces all your variants

#define FOO(...) printf(__VA_ARGS__)
3 
#define DEBUG 1  // or 2 or 4  etc.

#ifdef DEBUG == 1
// do debug 1 stuff
#endif

#ifdef DEBUG == 2
// do debug 2 stuff
#endif

-or-
you can use more complex logic to test
for debug modes e.g.

#ifdef (DEBUG && 3) == 3
// do both 1 and stuff
#endif

There are a lot of ways to do this
using binary or other logical constructs.

4

Thank you for your prompt reply. To test your suggestion I've written this test code:

#define DEBUG  1       // if 0 then debug does not display

#if DEBUG == 1
#define debug(...)    Serial.printf(__VA_ARGS__)
#else
#define debug(...) 
#endif

String test = "hello";

void setup() {
  Serial.begin(115200);
  while (!Serial);
     ;
  debug("this is a one test \n");
  debug("this is a two test %s \n", test );
  debug("three things  %d %d  \n", 1, 2);
  debug("four things  %d %d  \n", 3, 4, 5);
}

That works except with 4 variables it only prints 3. So I increased the number of dots from
2 to 4

#define debug(....)    Serial.printf(__VA_ARGS__)

but now I get a compile error

Compilation error: expected ')' after "..."

Would appreciate your comment please.

5

Do you mean that it not print "5" in the line below?

Do you know the syntax of the printf operator? It prints as many variables as the number of "%xx" placeholders you specified.
So you need to add another %d in your line that way:

debug("four things %d %d %d\n", 3, 4, 5);

6

Sorry, my error. Fixed it

debug("four things %d %d %d \n", 3, 4, 5);

So just use 3 dots and now works just fine.

Many thanks!

7

Thanks! I'm summarizing the good solution:

#define DEBUG_SWITCH true    // Switch on or off the debugging logs
#if DEBUG_SWITCH == true
    #define DEBUG_printf(...) Serial.printf(__VA_ARGS__)
#else
    #define DEBUG_printf(...)
#endif
// #include <LibPrintf.h>   // If your Arduino IDE does not know "printf", seek library "arduino-printf" at GitHub

while (!Serial) { }    // Wait until the serial bus to your Laptop is ready for transmission. Some types of microprocessor require this delay.
DEBUG_printf(F("\n[SETUP] This is the log of sketch '" __FILE__ "', compilled on " __DATE__ " " __TIME__ "\n"));

DEBUG_printf("[LOOP] I send integer numbers (e.g. %d), float numbers (%3.2f), hex numbers (0x%X) and strings (%s) to the serial port.\n", 1, 2.2, 3*3*3, "Four");
8

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