It happened to me many times that I submitted my solution without commenting out freopen and got compilation error! How virtual judges determines that I am using freopen/fopen? Interesting part is, I use - #define filein(x) freopen(x,"r",stdin) - #define fileout(x) freopen(x,"w",stdout)
it compiles when I do not call them. but it gets compilation error when I use filein("input.txt"); My question is, is it should be compilation error even though I use it! How they detect it!