hi,all i have 3 questions. 1. When i was trying wide character streams like wifstream ,wofstream , wcout etc. , i failed every time. My default locale is en_US.UTF-8. I created a test file , wrote a line Chinese "??" in that file. Then I try to use wifstream to read that file, after reading, i print it to stdout and write to another file. As a result , i got nothing. Assuming "input.txt" is the input file which contains Chinese character. BTW , input.txt is encoded with UTF-8. locale.global("en_US.UTF-8"); wifstream win("input.txt"); wcout<