Notes: Things to Avoid in C/C++

ref: Things to Avoid in C/C++

1. gets(): no internal checks means a potential overflow, use fgets() instead
   
2. fflush(stdin): effect undefined for input stream
3. feof() to exit a loop
4. system("pause"): no need for this expensive function, use getchar() instead
5. scanf(): a. leaves stuff in the input buffer to mess up your next input. b. quite a big function. c. for string, same problem as gets(). d. for char, use getchar() instead.
6. void main()