C# loop through two variables-CodePudding

I have 2 variables div1, div2 and want to get all value from them.

I can loop through one variable with foreach, but it's possible to get both divs InnerHtml?

HtmlWeb web = new HtmlWeb();

HtmlAgilityPack.HtmlDocument doc = web.Load(url);

var div1 = doc.DocumentNode.SelectNodes("//div[contains(@class,'class1')]");
var div2 = doc.DocumentNode.SelectNodes("//div[contains(@class,'class2')]");

                
foreach (HtmlNode div in div1)
{
    String text = div.InnerHtml;
    Debug.WriteLine(text);
}

CodePudding user response：

@mcjmzn, @Jonathan, and @Nenad answers are correct as far as printing all innerHtmls.

I'm guessing you want to print the first div1 innerHtml and then the first div2 innerHtml, and then second div1 innerHtml, and second div2 innerHtml, and so on. You'll want a regular loop instead of a foreach, and add checks to make sure you don't exceed div1 or div2 array lengths:

var div1Max = div1.Count;
var div2Max = div2.Count;
var overallMax = Math.Max(div1Max, div2Max);

for(var i = 0; i < overallMax; i  )
{
    if (i < div1Max)
    {
        String text1 = div1[i].InnerHtml;
        Debug.WriteLine(text1);
    }

    if (i < div2Max)
    {
        String text2 = div2[i].InnerHtml;
        Debug.WriteLine(text2);
    }
}

CodePudding user response：

You can use Concat extension method of IEnumerable to combine both collections of nodes.

HtmlWeb web = new HtmlWeb();

HtmlAgilityPack.HtmlDocument doc = web.Load(url);

var div1 = doc.DocumentNode.SelectNodes("//div[contains(@class,'class1')]");
var div2 = doc.DocumentNode.SelectNodes("//div[contains(@class,'class2')]");
var allNodes = div1.Concat(div2);
                
foreach (HtmlNode div in allNodes)
{
    String text = div.InnerHtml;
    Debug.WriteLine(text);
}

CodePudding user response：

Why don't you simply iterate one after another, instead of concatenating, etc?

foreach (HtmlNode div in div1)
{
    String text = div.InnerHtml;
    Debug.WriteLine(text);
}
foreach (HtmlNode div in div2)
{
    String text = div.InnerHtml;
    Debug.WriteLine(text);
}

CodePudding user response：

Create a container list at the beginning, add the results to it, and then loop through the container list:

var nodes = new HtmlNodeCollection();
nodes.Add(doc.DocumentNode.SelectNodes("//div[contains(@class,'class1')]"));
nodes.Add(doc.DocumentNode.SelectNodes("//div[contains(@class,'class2')]"));

foreach(HtmlNode node in nodes){
    Debug.WriteLine(node.InnerHtml);
}

It is also possible to build up a different query that will get all the class1s and class2s at the same time:

doc.DocumentNode.SelectNodes("//div[contains(@class,'class1') or contains(@class,'class2')]");

Edit after comment @ 22:24:56Z:

If there is only one result for each selector, you could simplify your approach something like this:

var text1 = doc.DocumentNode.SelectSingleNode("//div[contains(@class,'class1')]")?.InnerHtml ?? String.Empty;
var text2 = doc.DocumentNode.SelectSingleNode("//div[contains(@class,'class2')]")?.InnerHtml ?? String.Empty;

Those question marks are null-coalescing operators. See:

https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-coalescing-operator