問題：
The question was about plain c functions, not c++ static methods, as clarified in comments.問題是關於普通c函數，而不是c++ static方法，如註釋中所述。
I understand what a static variable is, but what is a static function?我明白什麼是static變量，但什麼是static函數？
And why is it that if I declare a function, let's say void print_matrix , in let's say ac (WITHOUT ah ) and include "ac" - I get "print_matrix@@....) already defined in a.obj" , BUT if I declare it as static void print_matrix then it compiles?爲什麼如果我聲明一個函數，讓我們說void print_matrix ，讓我們說ac （沒有ah ）幷包含"ac" - 我得到"print_matrix@@....) already defined in a.obj" ，但是如果我將它聲明爲static void print_matrix那麼它會編譯嗎？
UPDATE Just to clear things up - I know that including .c is bad, as many of you pointed out.更新只是爲了解決問題-正如你們中的許多人指出的那樣，我知道包括.c是不好的。 I just do it to temporarily clear space in main.c until I have a better idea of how to group all those functions into proper .h and .c files.我只是爲了暫時清除main.c空間，直到我更好地瞭解如何將所有這些函數分組到正確的.h和.c文件中。 Just a temporary, quick solution.只是一個臨時的、快速的解決方案。
解決方案：
參考一： https://stackoom.com/question/2LBy參考二： What is a “static” function in C?