[#bsl-basic_stringbuf-overflow-09c]
= xref:bsl.adoc[bsl]::xref:bsl/basic_stringbuf.adoc[basic_stringbuf]::overflow
:relfileprefix: ../../
:mrdocs:

Consumes data from the buffer; writes to the controlled sequence.

== Synopsis

Declared in `<bslstl_stringbuf.h>`

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

== Description

Informally, this function is called when the output buffer is full (or does not exist, as buffering need not actually be done). If a buffer exists, it is _consumed,_ with _some effect_ on the controlled sequence. (Typically, the buffer is written out to the sequence verbatim.) In either case, the character _c_ is also written out, if ___c_ is not `eof().`

For a formal definition of this function, see a good text such as Langer & Kreft, or [27.5.2.4.5]/3‐7.

A functioning output streambuf can be created by overriding only this function (no buffer area will be used).

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

====

== Return Value

eof() to indicate failure, something else (usually ___c,_ or not_eof())

== Parameters

[cols="1,4"]
|===
| Name| Description
| *__c*
| An additional character to consume.
|===


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