Effectively determine .NET Framework version

Verifying .NET Framework versions, especially 3.5 SP 1, is a common requirement for developers. However, just using Environment.Version() to get this information only gets you the base version, leaving out important details like service packs.

To do this, several methods exist:

For .NET 1-4

A simple and effective method is to retrieve data directly from the registry. For .NET versions 1 to 4, you can use the following code snippet:

RegistryKey installed_versions = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\NET Framework Setup\NDP");
string[] version_names = installed_versions.GetSubKeyNames();
// version names 以 'v' 開頭，例如 'v3.5'，在轉(zhuǎn)換前需要去除
double Framework = Convert.ToDouble(version_names[version_names.Length - 1].Remove(0, 1), CultureInfo.InvariantCulture);
int SP = Convert.ToInt32(installed_versions.OpenSubKey(version_names[version_names.Length - 1]).GetValue("SP", 0));

In this code, the "Framework" variable represents the highest installed version and "SP" holds the associated service pack number.

For .NET 4.5

For versions 4.5 and above, the official Microsoft documentation recommends the following method:

using System;
using Microsoft.Win32;


...


private static void Get45or451FromRegistry()
{
    using (RegistryKey ndpKey = RegistryKey.OpenBaseKey(RegistryHive.LocalMachine, RegistryView.Registry32).OpenSubKey("SOFTWARE\Microsoft\NET Framework Setup\NDP\v4\Full\")) {
        int releaseKey = Convert.ToInt32(ndpKey.GetValue("Release"));
        if (true) {
            Console.WriteLine("Version: " + CheckFor45DotVersion(releaseKey));
        }
    }
}


...


// 使用 >= 檢查版本將啟用前向兼容性，
// 但是您應(yīng)該始終在新版本的框架上編譯代碼，以確保您的應(yīng)用程序以相同的方式工作。
private static string CheckFor45DotVersion(int releaseKey)
{
    if (releaseKey >= 528040) {
        return "4.8 或更高版本";
    }
    if (releaseKey >= 461808) {
        return "4.7.2 或更高版本";
    }
    if (releaseKey >= 461308) {
        return "4.7.1 或更高版本";
    }
    if (releaseKey >= 460798) {
        return "4.7 或更高版本";
    }
    if (releaseKey >= 394802) {
        return "4.6.2 或更高版本";
    }
    if (releaseKey >= 394254) {
        return "4.6.1 或更高版本";
    }
    if (releaseKey >= 393295) {
        return "4.6 或更高版本";
    }
    if (releaseKey >= 393273) {
        return "4.6 RC 或更高版本";
    }
    if ((releaseKey >= 379893)) {
        return "4.5.2 或更高版本";
    }
    if ((releaseKey >= 378675)) {
        return "4.5.1 或更高版本";
    }
    if ((releaseKey >= 378389)) {
        return "4.5 或更高版本";
    }
    // 此行不應(yīng)該執(zhí)行。非空 release 密鑰應(yīng)該意味著
    // 已安裝 4.5 或更高版本。
    return "未檢測到 4.5 或更高版本";
}

This code utilizes the registry to determine the installed .NET Framework version and its corresponding service pack.

Using these technologies, developers can quickly and accurately determine the installed .NET Framework version, allowing them to make informed decisions and ensure compatibility with their applications.

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