[#BloombergLP-bdlsb-FixedMemInput]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlsb.adoc[bdlsb]::FixedMemInput
:relfileprefix: ../../
:mrdocs:

Provide a basic input stream buffer using client‐supplied memory.

== Synopsis

Declared in `<bdlsb_fixedmeminput.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class FixedMemInput;
----

== Description

This class, like `bdlsb::FixedMemInStreamBuf`, implements the input functionality of the `basic_streambuf` interface, using client‐supplied `char *` memory. It has an interface identical to `bdlsb::FixedMemInStreamBuf` but does _not_ inherit from `bsl::streambuf`. This implementation is advantageous for performance reasons, as the overhead of the initialization and virtual function calls of a `bsl::streambuf` can be undesirable. It is especially designed for streaming a very small amount of information from a fixed‐length buffer using a `bslx_genericinstream` when the number of characters read from the input is guaranteed not to exceed the length of the buffer. Note that this class is not designed to be derived from.

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlsb/FixedMemInput/char_type.adoc[`char_type`] 
| This `typedef` is an alias to `char`.
| xref:BloombergLP/bdlsb/FixedMemInput/int_type.adoc[`int_type`] 
| This `typedef` is an alias to `traits_type::int_type`.
| xref:BloombergLP/bdlsb/FixedMemInput/off_type.adoc[`off_type`] 
| This `typedef` is an alias to `traits_type::off_type`.
| xref:BloombergLP/bdlsb/FixedMemInput/pos_type.adoc[`pos_type`] 
| This `typedef` is an alias to `traits_type::pos_type`.
| xref:BloombergLP/bdlsb/FixedMemInput/traits_type.adoc[`traits_type`] 
| This `typedef` is an alias to `bsl::char_traits<char>`.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlsb/FixedMemInput/2constructor.adoc[`FixedMemInput`]         [.small]#[constructor]#
| Create a `FixedMemInput` using the specified buffer and length.
| xref:BloombergLP/bdlsb/FixedMemInput/capacity.adoc[`capacity`] 
| Return the size for the buffer held by this buffer, in bytes, supplied at construction.
| xref:BloombergLP/bdlsb/FixedMemInput/data.adoc[`data`] 
| Return the address of the non‐modifiable character buffer held by this stream buffer.
| xref:BloombergLP/bdlsb/FixedMemInput/in_avail.adoc[`in_avail`] 
| Return the number of characters available from the current read position in this stream buffer.
| xref:BloombergLP/bdlsb/FixedMemInput/length.adoc[`length`] 
| Return the number of characters remaining to be read.
| xref:BloombergLP/bdlsb/FixedMemInput/pubseekoff.adoc[`pubseekoff`] 
| Set the position indicator to a relative offset in this buffer.
| xref:BloombergLP/bdlsb/FixedMemInput/pubseekpos.adoc[`pubseekpos`] 
| Set the position indicator to the specified absolute position.
| xref:BloombergLP/bdlsb/FixedMemInput/pubsetbuf.adoc[`pubsetbuf`] 
| Reinitialize this stream buffer to use the specified character buffer.
| xref:BloombergLP/bdlsb/FixedMemInput/sbumpc.adoc[`sbumpc`] 
| Return the character at the current read position and advance.
| xref:BloombergLP/bdlsb/FixedMemInput/sgetc.adoc[`sgetc`] 
| Return the character at the current read position from this buffer, or `traits_type::eof()` if the end of the buffer is reached.
| xref:BloombergLP/bdlsb/FixedMemInput/sgetn.adoc[`sgetn`] 
| Read characters from this buffer into the specified destination.
| xref:BloombergLP/bdlsb/FixedMemInput/snextc.adoc[`snextc`] 
| Advance the read position and return the next character.
| xref:BloombergLP/bdlsb/FixedMemInput/sputbackc.adoc[`sputbackc`] 
| Put back the specified character if it matches the previous character.
| xref:BloombergLP/bdlsb/FixedMemInput/sungetc.adoc[`sungetc`] 
| Move the read position back one character and return that character.
|===



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