Is it possible to change the buffer size used in a C library at compile time?

Question

So, I am using a library for reading serial data. I have the source code of the library and it shows that the size of the serial data is something like this:

SOMETYPE ScopeArray[SCOPE_SIZE];

Where SCOPE_SIZE is defined by a user-defined compiler flag at compile time. Now my question is: If I'm using the library and not the source code, can I change the value of SCOPE_SIZE by recompiling my application not the library?

If this question doesn't make sense please let me know and I'll try my best to re-explain. Thanks!

No, as you point out `SCOPE_SIZE` is specified at compile time and it is then fixed in the resulting binary. — Sean Bright, Nov 20 '19 at 17:26
Can you change a compile-time constant without recompilng the library code that uses that constant? Uh ... no ;) — paulsm4, Nov 20 '19 at 17:27
Change it to a pointer and allocate it at startup/initialization time using malloc/mmap. — technosaurus, Nov 20 '19 at 19:28

score 1 · Answer 1 · answered Nov 20 '19 at 19:22

A compiled file is data, with a certain, fixed format. If you know the format of the compiled files, you can change them, but this can be difficult and error-prone, and doesn't really have much to do with C. It is not something that you can do by editing the C source code.

score 0 · Answer 2 · answered Nov 20 '19 at 19:16

The answer is no.

During preprocessing (before compilation, when the object file or library created) every macros are processed and it is not possible to modify them anymore.

There is a great thread under this question about the compilation and linking process: How does the compilation/linking process work?

Is it possible to change the buffer size used in a C library at compile time?

2 Answers2