問題:
All across our C code base, I see every macro defined the following way: 在我們的C代碼庫中,我看到每個宏都按以下方式定義:
#ifndef BEEPTRIM_PITCH_RATE_DEGPS
#define BEEPTRIM_PITCH_RATE_DEGPS 0.2f
#endif
#ifndef BEEPTRIM_ROLL_RATE_DEGPS
#define BEEPTRIM_ROLL_RATE_DEGPS 0.2f
#endif
#ifndef FORCETRIMRELEASE_HOLD_TIME_MS
#define FORCETRIMRELEASE_HOLD_TIME_MS 1000.0f
#endif
#ifndef TRIMSYSTEM_SHEARPIN_BREAKINGFORCE_LBS
#define TRIMSYSTEM_SHEARPIN_BREAKINGFORCE_LBS 50.0f
#endif
What is the rationale of doing these define checks instead of just defining the macros? 這些定義檢查的理由是什麼,而不僅僅是定義宏?
#define BEEPTRIM_PITCH_RATE_DEGPS 0.2f
#define BEEPTRIM_ROLL_RATE_DEGPS 0.2f
#define FORCETRIMRELEASE_HOLD_TIME_MS 1000.0f
#define TRIMSYSTEM_SHEARPIN_BREAKINGFORCE_LBS 50.0f
I can't find this practice explained anywhere on the web. 我無法在網絡上的任何地方找到這種做法。