[#bsl-basic_syncbuf-showmanyc]
= xref:bsl.adoc[bsl]::xref:bsl/basic_syncbuf.adoc[basic_syncbuf]::showmanyc
:relfileprefix: ../../
:mrdocs:

Investigating the data available.

== Synopsis

Declared in `<bslstl_syncbuf.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
virtual
streamsize
showmanyc();
----

== Description

If it returns a positive value, then successive calls to `underflow()` will not return `traits::eof()` until at least that number of characters have been supplied. If `showmanyc()` returns ‐1, then calls to `underflow()` or `uflow()` will fail. [27.5.2.4.3]/1

[NOTE]
====
Base class version does nothing, returns zero.

====

[NOTE]
====
The standard adds that the intention is not only that the calls [to underflow or uflow]will not return `eof()` but that they will return immediately.

====

[NOTE]
====
The standard adds that the morphemes of `showmanyc` are *es‐how‐many‐see,* not *show‐manic.*

====

== Return Value

An estimate of the number of characters available in the input sequence, or ‐1.


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