Change Preprocessor value in Objective-C

Question

Is there any way to change a preprocessor value like:

#define XValue 50

in Objective-C?

MByD · Accepted Answer · 2012-08-14 09:06:56Z

5

If you mean changing it during runtime, then no, as XValue is replaced with 50 before compilation.

If you mean changing it in the compilation, then yes, using #undef and #define.

Example:

XValue = 30; // NOT ALLOWED

#undef XValue // ALLOWED
#define XValue 30

answered Aug 14, 2012 at 9:06

MByD

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1 Comment

Gabrail Over a year ago

i mean during runtime .. anyway thanks so much and i will make your answer acceptable

JeremyP · Accepted Answer · 2012-08-14 09:08:08Z

2

#undef XValue
#define XValue 100

answered Aug 14, 2012 at 9:08

JeremyP

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Comments

Steve Jessop · Accepted Answer · 2012-08-14 09:21:22Z

1

What about:

int global_mutable_value = 50; 
#define XValue global_mutable_value

Or just

int XValue = 50;

You don't say why you want XValue to be a macro, so we can't tell whether your intentions for it would be satisfied by something that can change at runtime. If they would, use something that can change at runtime instead of a macro (I've used an extern variable). If they wouldn't, then of course you're out of luck.

answered Aug 14, 2012 at 9:21

Steve Jessop

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