NAME¶

std::basic_ios::exceptions - std::basic_ios::exceptions

Synopsis¶

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 <iostream>
#include <fstream>

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