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<h2 class="title"><a id="csharp"></a>Chapter 6. C# API</h2>
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<p>
<b>Table of Contents</b>
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<dl>
<dt>
<span class="sect1">
<a href="csharp.html#csharp_compat">Compatibility</a>
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<p>
A separate
<a class="link" href="build_win_csharp.html" title="Building the C# API">Visual Studio solution</a>
is provided to build the Berkeley DB C# classes,
the examples and the native support library.
</p>
<p>
The C# API requires version 2.0 of the .NET framework and expects that
it has already been installed on your system. For the sake of
discussion, we assume that the Berkeley DB source is in a directory
called db-<span class="emphasis"><em>VERSION</em></span>; for example, you downloaded a
Berkeley DB archive, and you did not change the top-level directory
name. The files related to C# are in four subdirectories of
db-<span class="emphasis"><em>VERSION</em></span>: csharp (the C# source files),
libdb_csharp (the C++ files that provide the "glue" between C# and
Berkeley DB,) examples_csharp (containing all example code) and
test\scr037 (containing NUnit tests for the API).
</p>
<p>
Building the C# API produces a managed assembly
<code class="filename">libdb_dotnet<span class="emphasis"><em>VERSION</em></span>.dll</code>,
containing the API, and two native libraries:
<code class="filename">libdb_csharp<span class="emphasis"><em>VERSION</em></span>.dll</code> and
<code class="filename">libdb<span class="emphasis"><em>VERSION</em></span>.dll</code>. (For all
three files, <span class="emphasis"><em>VERSION</em></span> is [MAJOR][MINOR], i.e. for
version 4.8 the managed assembly is
<code class="filename">libdb_dotnet48.dll</code>.) Following the existing
convention, native libraries are placed in either
<code class="filename">db-<span class="emphasis"><em>VERSION</em></span>\build_windows\Win32</code>or
<code class="filename">db-<span class="emphasis"><em>VERSION</em></span>\build_windows\x64</code>,
depending upon the platform being targeted. In all cases, the managed
assembly will be placed in
<code class="filename">db-<span class="emphasis"><em>VERSION</em></span>\build_windows\AnyCPU</code>.
</p>
<p>
Because the C# API uses P/Invoke, for your application to use Berkeley
DB successfully, the .NET framework needs to be able to locate the
native libaries. This means the native libraries need to either be
copied to your application's directory, the Windows or System
directory, or the location of the libraries needs to be added to the
<code class="literal">PATH</code> environment variable. See the MSDN
documentation of the DllImport attribute and Dynamic-Link Library
Search Order for further information.
</p>
<p>
If you get the following exception when you run, the .NET platform probably
is unable to locate the native libraries:
</p>
<pre class="programlisting">System.TypeInitializationException</pre>
<p>
To ensure that everything is running correctly, you may want to try a
simple test from the example programs in the
<code class="filename">db-<span class="emphasis"><em>VERSION</em></span>\examples_csharp</code>
directory.
</p>
<p>
For example, the ex_access sample program will prompt for text input
lines, which are then stored in a Btree database named
<code class="filename">access.db</code>. It is designed to be run from either
the
<code class="filename">db-<span class="emphasis"><em>VERSION</em></span>\build_windows\Debug</code>
or
<code class="filename">db-<span class="emphasis"><em>VERSION</em></span>\build_windows\Release</code>
directory. Try giving it a few lines of input text and then a blank
line. Before it exits, you should see a list of the lines you entered
display with data items. This is a simple check to make sure the
fundamental configuration is working correctly.
</p>
<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
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<div>
<h2 class="title" style="clear: both"><a id="csharp_compat"></a>Compatibility</h2>
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<p>
The Berkeley DB C# API has been tested with the Microsoft .NET Platform
(version 2.0) on Windows.
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