[#bsl-basic_stringbuf-pbackfail-0d]
= xref:bsl.adoc[bsl]::xref:bsl/basic_stringbuf.adoc[basic_stringbuf]::pbackfail
:relfileprefix: ../../
:mrdocs:

Tries to back up the input sequence.

== Synopsis

Declared in `<bslstl_stringbuf.h>`

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

== Description

[NOTE]
====
Base class version does nothing, returns eof().

====

== Return Value

eof() on failure, _some other value_ on success

== Parameters

[cols="1,4"]
|===
| Name| Description
| *__c*
| The character to be inserted back into the sequence.
|===

== Postconditions

* The constraints of `gptr(),` `eback(),` and `pptr()` are the same as for `underflow().`


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