Clean NSLog - No timestamp and program name

Question

I almost finishing a clean NSLog with this code:

#define NSLog(FORMAT, ...) printf("%s\n", [[NSString stringWithFormat:FORMAT, __VA_ARGS__] UTF8String]);

This work fine if I do this:

 NSLog(@"Show %@ message", @"this");

But, will fail if I user it

 NSLog(@"One argument");

because __VA_ARGS__ is nothing, so it produce

 printf("%s\n", [[NSString stringWithFormat:@"One argument",] UTF8String]);

So, the problem is the comma. Because this is macro, __VA_ARGS__ is nothing. So I can't do things like __VA_ARGS__==nil because will produce ==nil and will fail.

The question is simple: What to do when __VA_ARGS__ is nothing? Or only use comma when have more arguments.

xuzhe · Accepted Answer · 2017-12-17 14:59:58Z

62

Use this code (notice the ## part):

#define NSLog(FORMAT, ...) fprintf(stderr, "%s\n", [[NSString stringWithFormat:FORMAT, ##__VA_ARGS__] UTF8String]);

edited Dec 17, 2017 at 14:59

answered Sep 22, 2011 at 15:39

xuzhe

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5 Comments

Rodrigo Over a year ago

Work fine. I thought ## make no sense with __VA_ARGS__, but work.

Nathan Day Over a year ago

You should change the printf("%s\n" to fprintf( stderr, "%s\n" though. For various reasons, most importantly, printf goes to stout which is cached, stderr is not cached out is output straight away.

Rodrigo Over a year ago

Hum.. @Nathan Day. I saw things like this and didn't understand. But if it make things better, I will use :)

devios1 Over a year ago

Oh how sweet it is! :)

Olcay Ertaş Over a year ago

Is there a way to make this global. I still get time and application name for other libraries.

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