Weird error in c++

Question

What does this mean??
https://www.sololearn.com/post/127287/?ref=app
https://code.sololearn.com/cDDkVDrzNuYk/?ref=app

Answer 1

Yes, EOF cannot be used as a variable name. This gives no error.
https://code.sololearn.com/c481heYrdrYO/?ref=app

Answer 2

Thanks Sonic and Agent_I

Answer 3

The problem is the EOF variable. EOF is a macro definition with value of -1. Declaring varible with that will cause error

Answer 4

EOF can't be used because it's predefined. EOF - end of file.

Answer 5

Keyword cant be used as variable (key points)
Just confused the compiler pity compiler😆😆😆