C++ IOS Library - fail

Description

It is used to check whether either failbit or badbit is set. At least one of these flags is set when an error occurs during an input operation.failbit is generally set by an operation when the error is related to the internal logic of the operation itself; further operations on the stream may be possible. While badbit is generally set when the error involves the loss of integrity of the stream, which is likely to persist even if a different operation is attempted on the stream. badbit can be checked independently by calling member function bad −

`iostate` value (member constants)	indicates	functions to check state flags
`iostate` value (member constants)	indicates	`good()`	`eof()`	`fail()`	`bad()`	`rdstate()`
`goodbit`	No errors (zero value `iostate`)	`true`	`false`	`false`	`false`	`goodbit`
`eofbit`	End-of-File reached on input operation	`false`	`true`	`false`	`false`	`eofbit`
`failbit`	Logical error on i/o operation	`false`	`false`	`true`	`false`	`failbit`
`badbit`	Read/writing error on i/o operation	`false`	`false`	`true`	`true`	`badbit`

Declaration

Following is the declaration for ios::fail function.

bool fail() const;

Parameters

none

Return Value

true if badbit and/or failbit are set or else false otherwise.

Exceptions

Strong guarantee − if an exception is thrown, there are no changes in the stream.

Data Races

Accesses the stream object.

Concurrent access to the same stream object may cause data races.

ios.htm