C#四舍五入
double txtnum = Convert.ToDouble(this.textBox1.Text); if (txtnum < 0) { txtnum = Math.Round(txtnum + 5 / Math.Pow(10, 3), 2, MidpointRounding.AwayFromZero); } else { txtnum = Math.Round(Convert.ToDouble(txtnum), 2, MidpointRounding.AwayFromZero); } MessageBox.Show(txtnum.ToString());