How to create SharePoint Folders programmatically?

Question

How can I create a folder in SharePoint 2013 programmatically?

This is how I done the creation of a List. Is it possible to do it with folders?

    public static SPList GetOrCreateList(ref SPWeb web, SPList sourceList, string name, string description = null)
    {
        Guid ListGuid = new Guid();
        SPList _List = web.Lists.TryGetList(name);
        if (_List == null)
        {
            ListGuid = web.Lists.Add(name, description, (SPListTemplateType)sourceList.BaseTemplate);
            web.Update();
            _List = web.Lists[ListGuid];
        }
        return _List;
    }

Answer 1

Considering Folder is at one level, and not folders inside folders. This code will work.

Also make sure, in list setting -> Advance Settings -> Make "New Folder" command available? is set to Yes.

    public SPFolder GetOrCreateFolder(ref SPWeb web, SPList sourceList, string listName, string folderName)
    {
        SPFolder folder = null;
        if (sourceList == null)
        {
            folder = web.Folders[listName];
            if (folder != null)
            {
                if(!folder.SubFolders[folderName].Exists)
                    folder.SubFolders.Add(folderName);
                else
                    folder = folder.SubFolders[folderName];
            }
        }
        return folder;
    }

Answer 2

Try:

String url = site.Lists["LIST NAME"].RootFolder.ServerRelativeUrl.ToString();
SPFolderCollection folders = site.GetFolder(url).SubFolders; 

//Create new folder
folders.Add("FOLDER NAME");

Hope this helps