C# - Get all environment variables in sorted order-CodePudding

I'm trying to get a sorted list of all environment variables for logging purpose using System.Environment.GetEnvironmentVariables() which returns an IDictionary.

According to the documentation IDictionary does not provide any functionality for sorting: IDictionary Interface

The IDictionary interface allows the contained keys and values to be enumerated, but it does not imply any particular sort order.

As kind of workaround i came up with something like this:

var dictionary = Environment.GetEnvironmentVariables();

var keyList = dictionary.Keys.OfType<string>().ToList();
keyList.Sort();

int maxKeyLen = keyList.Max(key => ((string)key).Length);

string logMessage = "";

foreach (string key in keyList)
{
    logMessage = 
        logMessage   
        Environment.NewLine   
        (key   ": ").PadRight(maxKeyLen   2)   
        dictionary[key];
}

Console.WriteLine(logMessage);

Update

Due to the solution of @canton7 I changed the upper code to this:

var sortedEntries = Environment.GetEnvironmentVariables().Cast<DictionaryEntry>().OrderBy(entry => entry.Key);

int maxKeyLen = sortedEntries.Max(entry => ((string)entry.Key).Length);

string logMessage = "";

foreach (var entry in sortedEntries)
{
    logMessage =
        logMessage  
        Environment.NewLine  
        (entry.Key   ": ").PadRight(maxKeyLen   2)  
        entry.Value;
}

Console.WriteLine(logMessage);

CodePudding user response：

Environment.GetEnvironmentVariables() returns a non-generic IDictionary. IDictionary implements IEnumerable, and even though this isn't clear from the interface without reading the documentation, every member you get when iterating over it is a DictionaryEntry.

A DictionaryEntry is basically just a pre-generics KeyValuePair<object, object>.

Linq provides two methods for moving from a non-generic IEnumerable to a generic IEnumerable<T>: Cast<T>() and OfType<T>(). In this case, since we know that every element is a DictionaryEntry, we can use Cast<DictionaryEntry>().

So:

var entries = Environment.GetEnvironmentalVariables().Cast<DictionaryEntry>();

Now we've got an IEnumerable<DictionaryEntry>. We could just sort this:

var sortedEntries = entries.OrderBy(x => (string)x.Key);

Or we could turn it into a KeyValuePair<string, string> first to make it easier to work with:

var entries = Environment.GetEnvironmentalVariables().Cast<DictionaryEntry>()
    .Select(x => KeyValuePair.Create((string)x.Key, (string)x.Value));
var sortedEntries = entries.OrderBy(x => x.Key);