std::ios_base::sync_with_stdio
| 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:
In practice, this means that the C++ and the C streams use the same buffer, and therefore, can be mixed freely. In addition, synchronized C++ streams are guaranteed to be thread-safe (individual characters output from multiple threads may interleave, but no data races occur)
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.
Contents |
[edit] Parameters
| sync | - | the new synchronization setting |
[edit] Return value
synchronization state before the call to the function
[edit] Example
#include <iostream> #include <cstdio> int main() { std::cout.sync_with_stdio(false); std::cout << "a\n"; std::printf("b\n"); std::cout << "c\n"; }
Output:
b a c
[edit] See also
| writes to the standard C output stream stdout (global object) | |
| writes to the standard C error stream stderr, unbuffered (global object) | |
| writes to the standard C error stream stderr (global object) | |
