How to make all specific text bold in rchtextbox

In order to make specific text bold in a RichTextBox control, you’ll need to use the appropriate formatting options provided by the control’s API. Here’s an example of how you can achieve this in various programming languages:

// Assuming you have a RichTextBox control named "richTextBox1"

// Set the text you want to make bold
string text = "This is some bold text.";

// Find the starting position of the text in the RichTextBox
int startIndex = richTextBox1.Text.IndexOf(text);

// Set the selection start and length
richTextBox1.SelectionStart = startIndex;
richTextBox1.SelectionLength = text.Length;

// Apply bold formatting to the selected text
richTextBox1.SelectionFont = new Font(richTextBox1.Font, FontStyle.Bold);

Visual Basic .NET (Windows Forms):

' Assuming you have a RichTextBox control named "richTextBox1"

' Set the text you want to make bold
Dim text As String = "This is some bold text."

' Find the starting position of the text in the RichTextBox
Dim startIndex As Integer = richTextBox1.Text.IndexOf(text)

' Set the selection start and length
richTextBox1.SelectionStart = startIndex
richTextBox1.SelectionLength = text.Length

' Apply bold formatting to the selected text
richTextBox1.SelectionFont = New Font(richTextBox1.Font, FontStyle.Bold)

C# (WPF):

// Assuming you have a RichTextBox control named "richTextBox1"

// Set the text you want to make bold
string text = "This is some bold text.";

// Find the starting position of the text in the RichTextBox
TextRange range = new TextRange(richTextBox1.Document.ContentStart, richTextBox1.Document.ContentEnd);
int startIndex = range.Text.IndexOf(text);

if (startIndex >= 0)
{
    // Find the TextPointer for the start and end of the selected text
    TextPointer start = range.Start.GetPositionAtOffset(startIndex);
    TextPointer end = range.Start.GetPositionAtOffset(startIndex + text.Length);

    // Create a TextRange from the start and end TextPointers
    TextRange boldRange = new TextRange(start, end);

    // Apply bold formatting to the selected text
    boldRange.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.Bold);
}

These examples demonstrate how to find the starting position of the specific text within the RichTextBox control and then apply bold formatting to that text. Make sure to adapt the code to your specific programming environment and control names if needed.