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 · 2017-12-17T14:59:58.757

62

Use this code (notice the ## part):

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

edited Dec 17 '17 at 14:59

answered Sep 22 '11 at 15:39

xuzhe

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28

Work fine. I thought `##` make no sense with `__VA_ARGS__`, but work. – Rodrigo Sep 22 '11 at 17:15
4

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. – Nathan Day Sep 23 '11 at 03:20
Hum.. @Nathan Day. I saw things like this and didn't understand. But if it make things better, I will use :) – Rodrigo Sep 23 '11 at 13:19
Oh how sweet it is! :) – devios1 Apr 11 '15 at 20:17
Is there a way to make this global. I still get time and application name for other libraries. – Olcay Ertaş Dec 07 '17 at 08:35

Clean NSLog - No timestamp and program name

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