CODEWITHSUNDEEP
cc-preprocessor
aaaidan
aaaidan

Reputation: 7346

Using symbol name as string literal in #define function macro

I want a debug function-macro that works like this:

int myVar = 5;
PRINTVAR(myVar); // macro

// which expands to something like...
print("myVar: ");
println(myVar);

Basically, I want to use the identifier as a string literal as well as a variable.

I'm just getting a bit sick of repeating myself when I want to dump out a whole lot of variables to the stdout.

My silly attempt, which of course doesn't work:

#define PRINT_VAR(x) Serial.print("x: "); Serial.println(x);

Is this possible?

Upvotes: 3

Views: 6664

Answers (3)

gbjbaanb
gbjbaanb

Reputation: 52689

Look up the stringifying operator, #, when you use the macro id prefixed with this, it puts it as a string instead of expanding it.

Upvotes: 2

Halim Qarroum
Halim Qarroum

Reputation: 14103

Giving your code example, I don't know if you're talking about C or Java. However, here is I'll do in C :

#define DEBUG(X, ...) fprintf(x, __VA_ARGS__);

And to use it :

DEBUG(srderr, "my error\n");

Upvotes: 0

caf
caf

Reputation: 239331

The "stringizing operator" is designed for precisely this case:

#define PRINT_VAR(x) (print(#x ": "), println(x))

Upvotes: 10

Related Questions