[istream::sentry],
[ostream::sentry],
[iostate.flags]
Change: Specify use of explicit in existing boolean conversion functions.
Rationale: Clarify intentions, avoid workarounds.
Effect on original feature:
Valid C++ 2003 code that relies on implicit boolean conversions will fail to
compile with this International Standard. Such conversions occur in the
following conditions:
passing a value to a function that takes an argument of type bool;
using operator== to compare to false or true;
returning a value from a function with a return type of bool;
initializing members of type bool via aggregate initialization;
initializing a const bool& which would bind to a temporary.
[ios::failure]
Change: Change base class of std::ios_base::failure.
Rationale: More detailed error messages.
Effect on original feature:
std::ios_base::failure is no longer derived directly from
std::exception, but is now derived from std::system_error,
which in turn is derived from std::runtime_error. Valid C++ 2003 code
that assumes that std::ios_base::failure is derived directly from
std::exception may execute differently in this International Standard.
[ios.base]
Change: Flag types in std::ios_base are now bitmasks with values
defined as constexpr static members.
Rationale: Required for new features.
Effect on original feature:
Valid C++ 2003 code that relies on std::ios_base flag types being
represented as std::bitset or as an integer type may fail to compile
with this International Standard. For example:
#include <iostream>
int main() {
int flag = std::ios_base::hex;
std::cout.setf(flag); // error: setf does not take argument of type int
return 0;
}