三个按钮。以下为粗体按钮事件//设置粗体
        private void button1_Click(object sender, EventArgs e)
        {
            Font bold = this.richTextBox1.SelectionFont;
            if (bold.Bold)
            {
                if (bold.Italic)
                {
                    if (bold.Underline)
                    {
                        this.richTextBox1.SelectionFont = new Font(bold, FontStyle.Italic | FontStyle.Underline);
                    }
                    else
                        this.richTextBox1.SelectionFont = new Font(bold, FontStyle.Italic);
                }
                else if (bold.Underline)
                {
                    this.richTextBox1.SelectionFont = new Font(bold, FontStyle.Underline);
                }
                else
                    this.richTextBox1.SelectionFont = new Font(bold, FontStyle.Regular);
            }
            else if (bold.Italic)
            {
                if (bold.Underline)
                {
                    this.richTextBox1.SelectionFont = new Font(bold, FontStyle.Bold | FontStyle.Italic | FontStyle.Underline);
                }
                else
                    this.richTextBox1.SelectionFont = new Font(bold, FontStyle.Bold | FontStyle.Italic);
            }
            else if (bold.Underline)
            {
                this.richTextBox1.SelectionFont = new Font(bold, FontStyle.Bold | FontStyle.Underline);
            }
            else
                this.richTextBox1.SelectionFont = new Font(bold, FontStyle.Bold);        
        }其他2个按钮事件代码差不多。。当我切换输入法。选中字母和字体数字再单击按钮就报错。该如何解决?还有。。由于其他循环不怎么会。这代码用其他循环怎么写比较简洁一点?