static bool sync_with_stdio( bool sync = true );
Sets whether the standard std::cin, std::cout, std::cerr, std::clog, std::wcin, std::wcout, std::wcerr and std::wclog C++ streams are synchronized to the standard stdin, stdout, stderr and stdlog C streams after each input/output operation.
For a standard stream
str, synchronized with the C stream
f, the following pairs of functions have identical effect:
If the synchronization is turned off, the C++ standard streams are allowed to buffer their I/O independently, which may be considerably faster in some cases.
By default, all eight standard C++ streams are synchronized with their respective C streams.
It is implementation-defined if this function has any effect if called after some I/O occurred on the standard stream.
|sync||-||the new synchronization setting|
 Return value
synchronization state before the call to the function
b a c
 See also
| writes to the standard C output stream stdout|
| writes to the standard C error stream stderr, unbuffered|
| writes to the standard C error stream stderr|