Iterate through All SharePoint Web Applications, Site Collections, Sub-sites, Lists and List Items Programmatically

static void Main(string[] args)
{
	SPFarm farm = SPFarm.Local;
	//Get all SharePoint Web services
	SPWebService service = farm.Services.GetValue<SPWebService>("");

	foreach (SPWebApplication webapp in service.WebApplications)
	{
		 Console.WriteLine(webapp.Name);
		//Enumerate through each site collection
		foreach (SPSite site in webapp.Sites)
		{  
			//Console.WriteLine(site.Url);
			
			//Enumerate through each sub-site
			foreach (SPWeb web in site.AllWebs)
			{  
				//Console.WriteLine(web.Title);

				//Enumerate through each List
				foreach (SPList list in web.Lists)
				{
					//Console.WriteLine(list.Title);
				   //Enumerate through each list item
					 foreach(SPListItem Item in list.Items)
					 {
						//do something
					 }
				 }
			}
		}
	}
	 //To pause: 
	Console.ReadLine();
}

string site;
Console.WriteLine("Enter the Web Application URL:");
site = Console.ReadLine();

SPSite tmpRoot = new SPSite(site);
SPSiteCollection tmpRootColl = tmpRoot.WebApplication.Sites;

//Enumerate through each site collection
foreach (SPSite tmpSite in tmpRootColl)
{
   //Enumerate through each sub-site
	foreach (SPWeb tmpWeb in tmpSite.AllWebs)
	{
		//Enumerate through each List
		foreach (SPList tmpList in tmpWeb.Lists)
		{
			//Do something
		}
	 }                 
 }

static void Main(string[] args)
{
	SPWebApplication webApp = SPWebApplication.Lookup(new Uri("https://sharepoint.crescent.com"));

	foreach (SPContentDatabase cdb in webApp.ContentDatabases)
	{
		foreach (SPSite oSPSite in cdb.Sites)
		{
			Console.WriteLine("Site:" +oSPSite.RootWeb.Title +" at "+oSPSite.RootWeb.Url + " lives in the database:" + cdb.Name);
		}
	}
	Console.ReadLine();
}

# Get All Web Applications 
$WebApps=Get-SPWebApplication
foreach($webApp in $WebApps)
{ 
    foreach ($SPsite in $webApp.Sites)
    {
       # get the collection of webs
       foreach($SPweb in $SPsite.AllWebs)
        {
            write-host $SPweb.title ":" $spweb.URL
               foreach($list in $web.lists)
               {
					foreach($item in $list.items)
                    {
                        Write-Host $item.Title
                    }
               }
        }
    }
}

Get-SPWebApplication | Get-SPSite | Get-SPWeb -Limit All | ForEach-Object{ write-host Site Name: $_.Title, URL: $_.URL}

Get-SPSite "https://sharepoint.company.com/sales/" | Get-SPWeb -Limit All | Select Title, Url | Export-Csv -NoTypeInformation -Path "c:\sites.csv"

#Get all SharePoint content Databases
$ContentDatabases=  Get-SPContentDatabase 

#Iterate through each Database
Foreach($Database in $ContentDatabases)
{
	Write-host "`nContent Database: "$Database.Name 
	#Get all site collections of the Database
	$Sites = $Database.Sites
	foreach($site in $Sites)
	{
		Write-host $Site.URL
	}
}