[edit]Requirements

AFormattedOutputFunction is a member function ofstd::basic_ostream or a non-member function involvingstd::basic_ostream that performs the following operations:

1. Constructs an objectsentry of typestd::basic_ostream::sentry.
2. Ifbool(sentry) istrue, attempts to perform the desired output by inserting the characters into the output stream as if by callingrdbuf()->sputc(). Other public members ofstd::basic_ostream may also be used, but virtual members ofrdbuf() exceptoverflow(),xsputn() andsync() will never be called.
3. Destroyssentry and returns*this.

Ifsentry fails to be constructed, orbool(sentry) isfalse, no output takes place.

If the output could not be generated, callssetstate(std::ios_base::failbit), which can throw an exception.

If an exception is thrown during output, thenstd::ios_base::badbit is set in*this’s error state without causing astd::ios_base::failure to be thrown. If exceptions onbadbit are enabled in this stream'sexception mask (i.e.,(exceptions()& badbit)!=0), the exception is also rethrown.

When an exception is thrown from the formatted output function,sentry is also destroyed before leaving the function.

[edit]Padding

[edit]Standard library

The following standard library functions areFormattedOutputFunctions.

• basic_ostream::operator<<(std::basic_ostream&, int / long / double / void* / bool)
• operator<<(std::basic_ostream&, char)
• operator<<(std::basic_ostream&, char*)
• operator<<(std::basic_ostream&, const std::bitset&)
• operator<<(std::basic_ostream&, const std::basic_string&)
• operator<<, when called on the return value ofstd::put_money

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

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