Search and highlight text in Textbox or richTextBox in C#

How to highlight occurrences of a search term in text in Visual Studio C#

int index = 0; 
string temp = richTextBox1.Text;
 richTextBox1.Text = ""; 
richTextBox1.Text = temp;
 
while (index < richTextBox1.Text.LastIndexOf(textBox1.Text))
{
    // Searches the text in a RichTextBox control for a string within a range of text withing the control and with specific options applied to the search.
    richTextBox1.Find(textBox1.Text, index, richTextBox1.TextLength, RichTextBoxFinds.None);
    // Selection Color. This is added automatically when a match is found.
    richTextBox1.SelectionBackColor = Color.Yellow; 
    // After a match is found the index is increased so the search won't stop at the same match again. This makes possible to highlight same words at the same time.
    index = richTextBox1.Text.IndexOf(textBox1.Text, index) + 1; 
}

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