Compare version numbers without using split function

问题

How do I compare version numbers?

For instance:

x = 1.23.56.1487.5

y = 1.24.55.487.2

回答1:

Can you use the Version class?

http://msdn.microsoft.com/en-us/library/system.version.aspx

It has an IComparable interface. Be aware this won't work with a 5-part version string like you've shown (is that really your version string?). Assuming your inputs are strings, here's a working sample with the normal .NET 4-part version string:

static class Program
{
    static void Main()
    {
        string v1 = "1.23.56.1487";
        string v2 = "1.24.55.487";

        var version1 = new Version(v1);
        var version2 = new Version(v2);

        var result = version1.CompareTo(version2);
        if (result > 0)
            Console.WriteLine("version1 is greater");
        else if (result < 0)
            Console.WriteLine("version2 is greater");
        else
            Console.WriteLine("versions are equal");
        return;

    }
}

回答2:

If you can live with the major.minor.build.revision scheme you could use the .Net Version class. Otherwise you'd have to implement some kind of parsing from left to right and continuing until you have a difference or return that two versions are equal.

回答3:

In addition to @JohnD 's answer there might be a need to compare only partial version numbers without using Split('.') or other string <-> int conversion bloat. I've just written an extension method CompareTo with 1 additional argument - number of significant parts of version number to compare (between 1 and 4).

public static class VersionExtensions
{
    public static int CompareTo(this Version version, Version otherVersion, int significantParts)
    {
        if(version == null)
        {
            throw new ArgumentNullException("version");
        }
        if(otherVersion == null)
        {
            return 1;
        }

        if(version.Major != otherVersion.Major && significantParts >= 1)
            if(version.Major > otherVersion.Major)
                return 1;
            else
                return -1;

        if(version.Minor != otherVersion.Minor && significantParts >= 2)
            if(version.Minor > otherVersion.Minor)
                return 1;
            else
                return -1;

        if(version.Build != otherVersion.Build && significantParts >= 3)
            if(version.Build > otherVersion.Build)
                return 1;
            else
                return -1;

        if(version.Revision != otherVersion.Revision && significantParts >= 4)
            if(version.Revision > otherVersion.Revision)
                return 1;
            else
                return -1;

        return 0; 
    }
}

回答4:

public int compareVersion(string Version1,string Version2)
    {
        System.Text.RegularExpressions.Regex regex = new System.Text.RegularExpressions.Regex(@"([\d]+)");
        System.Text.RegularExpressions.MatchCollection m1 = regex.Matches(Version1);
        System.Text.RegularExpressions.MatchCollection m2 = regex.Matches(Version2);
        int min = Math.Min(m1.Count,m2.Count);
        for(int i=0; i<min;i++)
        {
            if(Convert.ToInt32(m1[i].Value)>Convert.ToInt32(m2[i].Value))
            {
                return 1;
            }
            if(Convert.ToInt32(m1[i].Value)<Convert.ToInt32(m2[i].Value))
            {
                return -1;
            }               
        }
        return 0;
    }

回答5:

If for some reason you are not allowed to use the compare-method of the Version directly (e.g. in a client-server scenario), another approach is to extract a long number from the version and then compare the numbers with each other. However, the number needs to have the following format: Two digits for Major, Minor and Revision and four for Build.

How to extract the version number:

var version = Assembly.GetExecutingAssembly().GetName().Version;

long newVersion = version.Major * 1000000000L + 
                   version.Minor * 1000000L + 
                   version.Build * 1000L + 
                   version.Revision;

And then somewhere else you can just compare:

if(newVersion > installedVersion)
{
  //update code
}

Note: the installedVersion is a previously extracted long number

来源：https://stackoverflow.com/questions/7568147/compare-version-numbers-without-using-split-function