define macro 1

[billbose]

 #define is_dig(x) ((x) >= '0' && (x) <= '9')

Can somebody tell me what does the above macros mean?

 

[Salem]

Can't you at least make an educated guess as to what it means?

Have you considered say isdigit() function in ctype.h as a better alternative?

--

 

[billbose]

Sorry, if my question seemed vague. Its not about the digit, but the way the macro works. FYI. I am totally new to this macro thing.
I am trying to understand somebody else's code.
His code has the following:

#define is_dig(x) ((x) >= '0' && (x) <= '9') 
is_dig(pattern[c]) ;

To my understanding, the preprocessor replaces pattern[c] with

is_dig( (pattern[c]) >= '0' && (pattern[c]) << '9' ;

Is that right?

 

[cpjust]

All occurances of

is_dig(pattern[c]);

will be replaced by:

(pattern[c]) >= '0' && (pattern[c]) <= '9';

Macros are like inline functions, except worse. You can't step through a macro while you're debugging and make finding and fixing bugs harder.
Functions or template functions are almost always better to use than macros.

 

[billbose]

Thank you cpjust for the explanation.