Chapter 127: IComparable

Section 127.1: Sort versions

Class:

public class Version : IComparable<Version>

{

public int[] Parts { get; }

public Version(string value)

{

if (value == null)

throw new ArgumentNullException();

if (!Regex.IsMatch(value, @"^[0-9]+(\.[0-9]+)*$")) throw new ArgumentException("Invalid format");

var parts = value.Split('.'); Parts = new int[parts.Length];

for (var i = 0; i < parts.Length; i++) Parts[i] = int.Parse(parts[i]);

}

public override string ToString()

{

return string.Join(".", Parts);

}

public int CompareTo(Version that)

{

if (that == null) return 1;

var thisLength = this.Parts.Length; var thatLength = that.Parts.Length;

var maxLength = Math.Max(thisLength, thatLength); for (var i = 0; i < maxLength; i++)

{

var thisPart = i < thisLength ? this.Parts[i] : 0; var thatPart = i < thatLength ? that.Parts[i] : 0; if (thisPart < thatPart) return -1;

if (thisPart > thatPart) return 1;

}

return 0;

}

}

Test:

Version a, b;

a = new Version("4.2.1"); b = new Version("4.2.6");

a.CompareTo(b); // a < b : -1

a = new Version("2.8.4"); b = new Version("2.8.0");

a.CompareTo(b); // a > b : 1

a = new Version("5.2"); b = null;

a.CompareTo(b); // a > b : 1

a = new Version("3");

b = new Version("3.6"); a.CompareTo(b); // a < b : -1

var versions = new List<Version>

{

new Version("2.0"), new Version("1.1.5"), new Version("3.0.10"), new Version("1"), null,

new Version("1.0.1")

};

versions.Sort();

foreach (var version in versions) Console.WriteLine(version?.ToString() ?? "NULL");

Output:

NULL 1 1.0.1 1.1.5 2.0 3.0.10

Demo:

Live demo on Ideone