[#BloombergLP-bdlde-Utf8CheckingInStreamBufWrapper-pbackfail]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlde.adoc[bdlde]::xref:BloombergLP/bdlde/Utf8CheckingInStreamBufWrapper.adoc[Utf8CheckingInStreamBufWrapper]::pbackfail
:relfileprefix: ../../../
:mrdocs:

Back up input one byte. Return the byte at the new position, or `eof` with the state of this object unchanged on failure. If the optionally specified `c` is not `eof`, substitute `c` for the previous byte and return that value. If `c` is `eof`, do not substitute it for the previous byte and return the byte was there, or if the previous byte is unknown, fail. If values of `c` that are not `eof` are specified, this function will succeed for at least 8 successive calls, possibly many more times. The behavior is undefined unless `c` is either `eof` or a value representable as a `char_type`. Note that this is forwarded to with a `char_type` passed to `c` by the public method `sputbackc` in the base class, and called with `eof` passed to `c` by the public method `sungetc` in the base class.

== Synopsis

Declared in `<bdlde_utf8checkinginstreambufwrapper.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
virtual
int_type
pbackfail(int_type c = traits_type::eof()) override;
----


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