C Programming How to convert macro to function

Question

I need to know how to convert any #define for .c (source) and .h (header) files.

#define ELAPSED_TIME(currentTime, startTime) (currentTime - startTime)

What do you mean by convert? If you mean replace then that can be done in pre-compile step e.g. gcc -E my_source.c — Sandy
– Sandy, Commented Aug 14, 2018 at 11:07
Add suitable types, braces, return, and a semicolon. (That particular macro is broken, by the way. ELAPSED_TIME(3, 1+1); should be 1, but is 3.) — molbdnilo
– molbdnilo, Commented Aug 14, 2018 at 11:11

Mike · Accepted Answer · 2018-08-14 11:17:30Z

3

for example:

int elapsed_Time (int currentTime, int startTime)
{
    return (currentTime - startTime);
}

answered Aug 14, 2018 at 11:17

Mike

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Comments

shailesh tripathi · Accepted Answer · 2018-08-14 11:21:14Z

Preprocessed macros are simply text replacement , so if you convert such macro in function then you must bind it with some type , here looking at macro definition I am not sure generic (void*) type will work here. In c++ you can templatise the same, but this is simply replacement so if you have genric usage like for float/char/int/uint/long so better to keep it or templatize it in c++ or use (void*) in c function and do the subtraction on lowest unit level (eg char by char ).

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