CODEWITHSUNDEEP
c#hashtable
jshaf
jshaf

Reputation: 309

Iterating over c# HashTable and changing the value. Additional information: Collection was modified; enumeration operation may not execute

I am trying to iterate over a HashTable and update the value provided it passes some conditions. Here is the code.

public static Hashtable AssembliesGlobal= new Hashtable();

public static void populateHash(){

   NDepend.Path.IAbsolutePath assemblyName; 
   NDepend.Path.IAbsolutePath projectName;

   for (int i = 0; i < someList.Count(); i++)
      {

         if (someList[i].AssembliesUsed.Count() > 0)
            {
                assemblyName = getAssemblyQuery[i].a.FilePath;
                if (getAssemblyQuery[i].a.VisualStudioProjectFilePath != null)
                {
                    List<IAbsolutePath> thirdPartyList = new List<IAbsolutePath>();
                    projectName = getAssemblyQuery[i].a.VisualStudioProjectFilePath;
                    thirdPartyList.Add(assemblyName);
                    AssembliesGlobal.Add(projectName, thirdPartyList);
                }

            }
        }
     }


public static void parseCsproj()
{

    foreach (IAbsoluteFilePath key in AssembliesGlobal.Keys)
    {
        XmlDocument xmldoc = new XmlDocument();
        xmldoc.Load(key.FileInfo.FullName);
        XmlNodeList references = xmldoc.GetElementsByTagName("ProjectReference");
        XmlNodeList hintReferences = xmldoc.GetElementsByTagName("HintPath");
        if (references.Count >= 1 || hintReferences.Count >= 1)
        {
            for (int i = 0; i < references.Count; i++)
            {
                string path = references[i].Attributes[0].Value;
                if(path.Contains("3rdParty")){
                    AssembliesGlobal[key] = path;
                }

            }

            for (int i = 0; i < hintReferences.Count; i++)
            {
                string path = hintReferences[i].InnerText;
                if (path.Contains("3rdParty"))
                {
                    AssembliesGlobal[key] = path;
                }
            }
        }
    }
}

AssembliesGlobal is a hashtable with the structure of:

AssembliesGlobal = {key => []}

I would like to append to the array that is the value of key. After running the debugger in VS I keep getting a Additional information: Collection was modified; enumeration operation may not execute. error. I am aware that you cannot iteratively update a HashTable and I am wondering what a work around may be in this context. I new to this language.

Upvotes: 0

Views: 1093

Answers (2)

Stephen York
Stephen York

Reputation: 1449

In response to your comment on my comment above, is this what you're after (bearing in mind it's a stripped down example). 

var AssembliesGlobal = new Dictionary<string, List<string>>();
AssembliesGlobal.Add("Steve", new List<string> { "1", "2", "3"});
foreach (var key in AssembliesGlobal.Keys)
{
    AssembliesGlobal[key].Add("4");
}

Upvotes: 2

Blorgbeard
Blorgbeard

Reputation: 103555

You can make a copy of the list to iterate over, by casting and adding a .ToList():

foreach (var key in AssembliesGlobal.Keys.Cast<IAbsoluteFilePath>().ToList())

Note that you need the .Cast because Hashtable is non-generic. As others have mentioned, the modern way to do this is Dictionary<K,V>.

Upvotes: 6

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