string countryCode = "de";
try {
    RegionInfo info = new RegionInfo(countryCode);
}
catch (ArgumentException argEx)
{
    // The code was not a valid country code
}

您也可以在您的问题中说明,检查它是否是德语的有效国家代码.然后,您只需传递具体的文化名称和国家代码.

string language = "de";
string countryCode = "de";
try {
    RegionInfo info = new RegionInfo(string.Format("{0}-{1}",language,countryCode));
}
catch (ArgumentException argEx)
{
    // The code was not a valid country code for the specified language
}