c#在richtextbox内实现简易的c++代码自动提示的代码

以下是一个简易的C#代码示例，可以在RichTextBox内实现简易的C++代码自动提示：

private string[] cplusplusHints = { "if", "else", "for", "while", "do", "switch", "case", "break", "continue" };
private ComboBox cbHints;

private void Form1_Load(object sender, EventArgs e)
{
    // 初始化ComboBox
    cbHints = new ComboBox();
    cbHints.Visible = false;
    cbHints.DropDownStyle = ComboBoxStyle.DropDownList;
    cbHints.SelectedIndexChanged += new EventHandler(cbHints_SelectedIndexChanged);
    this.Controls.Add(cbHints);
}

private void richTextBox1_TextChanged(object sender, EventArgs e)
{
    string[] words = richTextBox1.Text.Split(' ');
    string lastWord = words[words.Length - 1];
    string hint = "";

    // 检查最后一个单词是否匹配任何提示项
    foreach (string s in cplusplusHints)
    {
        if (s.StartsWith(lastWord))
        {
            hint = s;
            break;
        }
    }

    // 如果有提示项则弹出ComboBox
    if (hint != "")
    {
        cbHints.Items.Clear();
        cbHints.Items.AddRange(cplusplusHints.Where(s => s.StartsWith(lastWord)).ToArray());
        cbHints.Left = richTextBox1.Left;
        cbHints.Top = richTextBox1.Bottom;
        cbHints.Width = richTextBox1.Width;
        cbHints.Visible = true;
        cbHints.DroppedDown = true;
    }
    else
    {
        cbHints.Visible = false;
    }
}

private void cbHints_SelectedIndexChanged(object sender, EventArgs e)
{
    // 将选择的提示项插入到RichTextBox中
    richTextBox1.Text += cbHints.SelectedItem.ToString().Substring(richTextBox1.Text.Split(' ')[richTextBox1.Text.Split(' ').Length - 1].Length);
    richTextBox1.Focus();
    richTextBox1.SelectionStart = richTextBox1.Text.Length;
}

private void richTextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar == 13)
    {
        cbHints.Visible = false;
    }
}

这段代码实现了一个简单的C++代码提示，只包含了if、else、for、while、do、switch、case、break和continue等关键字。可以根据实际需求添加更多的提示项。