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POHow to convert CIDR to network and IP address range in C#?
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  1. POHow to convert CIDR to network and IP address range in C#?
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    copied!<p>I have been looking around quite a bit to find some C# code to convert a network in CIDR notation (72.20.10.0/24) to an IP address range, without much luck. There are some threads about CIDR on stackoverlow, but none seems to have any C# code and cover exactly what I need. So I decided to cook it myself, and I did not want the code to rely on System.Net for any conversions in this version. </p> <p>Perhaps it may be of help to someone. </p> <p>References: </p> <p><a href="https://stackoverflow.com/questions/218604/whats-the-best-way-to-convert-from-network-bitcount-to-netmask">What&#39;s the best way to convert from network bitcount to netmask?</a></p> <p>"Whatmask" C code from <a href="http://www.laffeycomputer.com/whatmask.html" rel="nofollow noreferrer">http://www.laffeycomputer.com/whatmask.html</a></p> <p>Usage: </p> <pre><code>uint startIP, endIP; Network2IpRange("72.20.10.0/24", out startIP, out endIP); </code></pre> <p>The code assumes 32 bits for everything. </p> <pre class="lang-cs prettyprint-override"><code>static void Network2IpRange(string sNetwork, out uint startIP, out uint endIP) { uint ip, /* ip address */ mask, /* subnet mask */ broadcast, /* Broadcast address */ network; /* Network address */ int bits; string[] elements = sNetwork.Split(new Char[] { '/' }); ip = IP2Int(elements[0]); bits = Convert.ToInt32(elements[1]); mask = ~(0xffffffff &gt;&gt; bits); network = ip &amp; mask; broadcast = network + ~mask; usableIps = (bits &gt;30)?0:(broadcast - network - 1); if (usableIps &lt;= 0) { startIP = endIP = 0; } else { startIP = network + 1; endIP = broadcast - 1; } } public static uint IP2Int(string IPNumber) { uint ip = 0; string[] elements = IPNumber.Split(new Char[] { '.' }); if (elements.Length==4) { ip = Convert.ToUInt32(elements[0])&lt;&lt;24; ip += Convert.ToUInt32(elements[1])&lt;&lt;16; ip += Convert.ToUInt32(elements[2])&lt;&lt;8; ip += Convert.ToUInt32(elements[3]); } return ip; } </code></pre> <p>Feel free to submit your improvements. </p>
 

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