[C Language] self-reflection

I feel that my C language has been well learned. Others also say that my c is okay, but I went to the interview today. Although all the questions are existing on the internet, I made a mistake when I showed it to their technicians. When I looked at it again, I found it was really wrong. I was wondering: Why didn't I see it at the time?

So, alas, you can't miss a small detail, even on the Internet, or be proud of yourself, but I have to feel that there are still many things to learn. I have to work hard to think of it as a whisper. However, I still need it when I blow it, haha.