windows - What's the difference between strtok_r and strtok_s in C?

Question

I'm trying to use this function in a C program that needs to be able to compile in Linux and Windows. At first I tried using strtok_r, but then when I compiled on windows, it complained about the function not existing and said it would assume it's an extern function, but then failed. I then used strtok_s and it compiled! Then I tried on Linux but now it's complaining that there is an "undefined reference to 'strtok_s'".

Is one a windows only function and the other a linux function??? What can I do to make it compile on both?

Answer 1

strtok_s is simply the Windows version of strtok_r which is standard everywhere else.

One (common I would think) way to make a program portable when it comes to functions like strtok_s/strtok_r is to use the preprocessor:

#if defined(_WIN32) || defined(_WIN64)
/* We are on Windows */
# define strtok_r strtok_s
#endif

As the prototypes and functionality is the same, you can now use only strtok_r.