How i can avoid buffer overflow?

Answer 1

Read the last part of this article:
https://www.thegeekstuff.com/2013/06/buffer-overflow/#:~:text=A%20buffer%20is%20said%20to,variable%20that%20references%20the%20buffer
Also you can see this:
https://www.synopsys.com/blogs/software-security/detect-prevent-and-mitigate-buffer-overflow-attacks/
https://stackoverflow.com/q/22138478