std::basic_ios<CharT,Traits>:: exceptions

From cppreference.com
C++
Input/output library
std::basic_ios
std:: ios_base :: iostate exceptions ( ) const ;
(1)
void exceptions ( std:: ios_base :: iostate except ) ;
(2)

Gets and sets the exception mask of the stream. The exception mask determines which error states trigger exceptions of type failure .

1) Returns the exception mask.
2) Sets the exception mask to except . If the stream has an error state covered by the exception mask when called, an exception is immediately triggered.

Parameters

except - exception mask

Return value

1) The current exception mask.
2) (none)

Notes

This section is incomplete
Reason: discuss LWG2349 and link from ios_base::clear, and from (un)formatted(i/o)utputfunction requirement pages (or perhaps the behavior should be fully elaborated on the requirement pages and linked from here). See also stackoverflow.com/a/35089910

Example

Run this code 
#include <fstream>
#include <iostream>
 
int main() 
{
    int ivalue;
    try
    {
        std::ifstream in("in.txt");
        in.exceptions(std::ifstream::failbit); // may throw
        in >> ivalue; // may throw
    }
    catch (const std::ios_base::failure& fail)
    {
        // handle exception here
        std::cout << fail.what() << '\n';
    }
}

Possible output: 

basic_ios::clear: iostream error
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