It is used in standard Input / Output Streams Library.
Following is the declaration for iosstream function.
Including this header may automatically include other headers, such as <ios>, <streambuf>, <istream>, <ostream> and/or <iosfwd>.
Including <iostream> automatically includes also <ios>, <streambuf>, <istream>, <ostream> and <iosfwd>.
The objects of iosstream should be like this −
|1||cin||Standard input stream|
|2||cout||Standard output stream|
|3||cerr||Standard output stream for errors|
|4||clog||Standard output stream for logging|
|1||wcin||Standard input stream (wide)|
|2||wcout||SStandard output stream (wide)|
|3||wcerr||Standard output stream for errors (wide-oriented)|
|4||wclog||Standard output stream for logging (wide)|