为什么当尝试为richTextBox中的文本的多于一部分的颜色着色时却根本没有着色？

Question

It will color one part of text.

In listView selectedindex event

void lvnf_SelectedIndexChanged(object sender, EventArgs e)
{
    if (ListViewCostumControl.lvnf.SelectedItems.Count > 0)
    {
        string word = textBox1.Text;
        string[] test = word.Split(',');
        foreach (string myword in test)
        {
            richTextBox1.Text = File.ReadAllText(ListViewCostumControl.lvnf.Items[ListViewCostumControl.lvnf.SelectedIndices[0]].Text);
            FileInfo fi = new FileInfo(ListViewCostumControl.lvnf.Items[ListViewCostumControl.lvnf.SelectedIndices[0]].Text);
            HighlightPhrase(richTextBox1, myword, Color.Yellow);
            if (myword == "Form1")
            {
                break;
            }
        }
    }
}

And

static void HighlightPhrase(RichTextBox box, string phrase, Color color)
{
    int pos = box.SelectionStart;
    string s = box.Text;
    for (int ix = 0; ; )
    {
        int jx = s.IndexOf(phrase, ix, StringComparison.CurrentCultureIgnoreCase);
        if (jx < 0) { break; }
        box.SelectionStart = jx;
        box.SelectionLength = phrase.Length;
        box.SelectionColor = color;
        ix = jx + 1;
    }
    box.SelectionStart = pos;
    box.SelectionLength = 0;
}

When i added this break part:

if (myword == "Form1")
{
    break;
}

It's working it will color all the places in richTextBox with Form1. But if i remove this break part it should color all places in the richTextBox that the texts is exist from the string array variable test.

In test i have: Form1,form2,hi,44

But it's not coloring at all nothing.

Answer 1

When you removed the if (myword == "Form1") break; part, the code pretty much becomes:

foreach (string myword in test)
            {
                richTextBox1.Text = ......;
                HighlightPhrase(richTextBox1, myword, Color.Yellow);                       
             }

which in your case since your test string is Form1,form2,hi,44, it becomes:

 richTextBox1.Text = ......;
 HighlightPhrase(richTextBox1, "Form1", Color.Yellow);
 richTextBox1.Text = ......;
 HighlightPhrase(richTextBox1, "form2", Color.Yellow);
 richTextBox1.Text = ......;
 HighlightPhrase(richTextBox1, "hi", Color.Yellow);
 richTextBox1.Text = ......;
 HighlightPhrase(richTextBox1, "44", Color.Yellow);

As you can see the text property keeps changing and thus the formatting gets reset (or applied to your entire string in some cases).

Making a few assumptions, I would change your code to:

if (ListViewCostumControl.lvnf.SelectedItems.Count > 0)
        {
            var selectedText = ListViewCostumControl.lvnf.Items[ListViewCostumControl.lvnf.SelectedIndices[0]].Text;
            richTextBox1.Text = File.ReadAllText(selectedText);
            FileInfo fi = new FileInfo(selectedText);  //not used!

            string word = textBox1.Text;
            string[] test = word.Split(',');
            foreach (string myword in test)
            {                    
                HighlightPhrase(richTextBox1, myword, Color.Yellow);
            }
          }