C# detect latest .net framework installed on PC

 static void getnetversiondemo()
        {
            using (registrykey ndpkey = registrykey.openbasekey(registryhive.localmachine, registryview.registry32).opensubkey(@"software\microsoft\net framework setup\ndp\"))
            {
                foreach(var versionkeyname in ndpkey.getsubkeynames())
                {
                    //skip .net framework 4.5 version information.
                    if(versionkeyname=="v4")
                    {
                        continue;
                    }

                    if(versionkeyname.startswith("v"))
                    {
                        registrykey versionkey = ndpkey.opensubkey(versionkeyname);

                        //get the .net framework version value.
                        var name = (string)versionkey.getvalue("version", "");

                        //get the service pack number.
                        var sp = versionkey.getvalue("sp", "").tostring();

                        //get the installation flag,or an empty string if there is none.
                        var install = versionkey.getvalue("install", "").tostring();

                        if(string.isnullorempty(install))
                        {
                            console.writeline($"{versionkeyname} {name}");
                        }
                        else
                        {
                            if(!string.isnullorempty(sp) && install=="1")
                            {
                                console.writeline($"{versionkeyname} {name} sp{sp}");
                            }
                        }

                        if(!string.isnullorempty(name))
                        {
                            continue;
                        }

                        foreach(var subkeyname in versionkey.getsubkeynames())
                        {
                            registrykey subkey = versionkey.opensubkey(subkeyname);
                            name = (string)subkey.getvalue("version", "");
                            if(!string.isnullorempty(name))
                            {
                                sp = subkey.getvalue("sp", "").tostring();
                            }

                            install = subkey.getvalue("install", "").tostring();
                            if(string.isnullorempty(install))
                            {
                                console.writeline($"{versionkeyname} {name}");
                            }
                            else
                            {
                                if((!string.isnullorempty(sp)) && install=="1")
                                {
                                    console.writeline($"{subkeyname} {name}  sp{sp}");
                                }
                                else
                                    if(install=="1")
                                {
                                    console.writeline($"{subkeyname} {name}");
                                }
                            }
                        }
                    }
                }
            }
        }

 

using microsoft.win32;

static void main(string[] args)
        {
            getdotnetframeworkversion();
            console.readline();
        }

        static void getdotnetframeworkversion()
        {
            const string subkey = @"software\microsoft\net framework setup\ndp\v4\full";
            using (var ndpkey = registrykey.openbasekey(registryhive.localmachine, registryview.registry32).opensubkey(subkey))
            {
                if(ndpkey!=null && ndpkey.getvalue("release")!=null)
                {
                    var objresult = ndpkey.getvalue("release");
                    var versionresult = checkfor45plusversion((int)objresult);
                    console.writeline($".net framework version:{versionresult}");
                }
                else
                {
                    console.writeline(".net framework version 4.5 or later is not detected!");
                }
            }
        }

        //convert the main.minor.build.revision
        static string checkfor45plusversion(int releasekey)
        {             
            if(releasekey>=528040)
            {
               return "4.8 or later";
            }

            if(releasekey>=461808)
            {
                return "4.7.2";
            }

            if(releasekey>=461308)
            {
                return "4.7.1";
            }

            if (releasekey >= 460798)
            {
                return "4.7";
            }

            if(releasekey>=394802)
            {
                return "4.6.2";
            }

            if(releasekey>=394254)
            {
                return "4.6.1";
            }

            if(releasekey>=393295)
            {
                return "4.6";
            }

            if(releasekey>=393295)
            {
                return "4.5.2";
            }

            if(releasekey>=378675)
            {
                return "4.5.1";
            }

            if(releasekey>=378389)
            {
                return "4.5";
            }

            return "no 4.5 or later version detected!";
        }