+ int sync() { return logBuf->pubsync(), buf->pubsync(); }
+ int overflow(int c) { return log(buf->sputc((char)c), "<< "); }
+ int underflow() { return buf->sgetc(); }
+ int uflow() { return log(buf->sbumpc(), ">> "); }
+
+ streambuf *buf, *logBuf;
+
+ int log(int c, const char* prefix) {
+
+ static int last = '\n'; // Single log file
+
+ if (last == '\n')
+ logBuf->sputn(prefix, 3);
+
+ return last = logBuf->sputc((char)c);
+ }
+};
+
+class Logger {
+
+ Logger() : in(cin.rdbuf(), file.rdbuf()), out(cout.rdbuf(), file.rdbuf()) {}
+ ~Logger() { start(false); }
+
+ ofstream file;
+ Tie in, out;
+
+public:
+ static void start(bool b) {
+
+ static Logger l;
+
+ if (b && !l.file.is_open())
+ {
+ l.file.open("io_log.txt", ifstream::out);
+ cin.rdbuf(&l.in);
+ cout.rdbuf(&l.out);
+ }
+ else if (!b && l.file.is_open())
+ {
+ cout.rdbuf(l.out.buf);
+ cin.rdbuf(l.in.buf);
+ l.file.close();
+ }
+ }
+};