[#bsl-basic_stringbuf-pbackfail-07]
= xref:bsl.adoc[bsl]::xref:bsl/basic_stringbuf.adoc[basic_stringbuf]::pbackfail
:relfileprefix: ../../
:mrdocs:

`pbackfail` overloads

== Synopses

Declared in `<bslstl_stringbuf.h>`

Tries to back up the input sequence.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
virtual
int_type
xref:bsl/basic_stringbuf/pbackfail-0d.adoc[pbackfail](int_type __c = traits_type::eof());
----

[.small]#xref:bsl/basic_stringbuf/pbackfail-0d.adoc[_» more..._]#

Put back the specified `character` into the input sequence so that the next character read from the input sequence will be `character`. If `character` is either `traits_type::eof()` or is the same as the previously read character from the input sequence, then adjust the current input position, `gptr`, back one position. If `character` is neither `traits_type::eof()` nor the character previously read from the input sequence, but this string buffer was opened for writing (`ios_base::out`), then adjust the input sequence back one position and write `character` to that position. Return the character that was put back on success and `traits_type::eof()` if either the input position is currently at the beginning of the sequence or if the previous character in the input sequence is not `character` and this buffer was not opened for writing.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
virtual
xref:bsl/basic_stringbuf/int_type.adoc[basic_stringbuf<CHAR_TYPE, CHAR_TRAITS, ALLOCATOR>::int_type]
xref:bsl/basic_stringbuf/pbackfail-05.adoc[pbackfail](xref:bsl/basic_stringbuf/int_type.adoc[int_type] character = traits_type::eof());
----

[.small]#xref:bsl/basic_stringbuf/pbackfail-05.adoc[_» more..._]#

== 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().`


[.small]#Created with https://www.mrdocs.com[MrDocs]#