Question

private void cbService1_SelectedIndexChanged(object sender, EventArgs e)
        {
            string str = "Data Source=DELL-PC\\SQLEXPRESS;Initial Catalog=Salon Primik; Integrated Security = True";
            SqlConnection cn = new SqlConnection(str);

            string Name = cbService1.SelectedValue.ToString();
            cn.Open();
            string Sql = "select Amount from Service where Name='" + Name + "'";

            SqlCommand cmd = new SqlCommand(Sql, cn);
            SqlDataReader dr;
            dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                lblService1.Text = dr["Amount"].ToString();
                int i1 = Convert.ToInt32(lblService1.Text);
                total(i1,0);

            }
            dr.Close();
            cn.Close();
        }

private void cbService2_SelectedIndexChanged(object sender, EventArgs e)
        {
            string str = "Data Source=DELL-PC\\SQLEXPRESS;Initial Catalog=Salon Primik; Integrated Security = True";
            SqlConnection cn = new SqlConnection(str);

            string Name = cbService2.SelectedValue.ToString();
            cn.Open();
            string Sql = "select Amount from Service where Name='" + Name + "'";

            SqlCommand cmd = new SqlCommand(Sql, cn);
            SqlDataReader dr;
            dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                lblService2.Text = dr["Amount"].ToString();
                int i2 = Convert.ToInt32(lblService2.Text);
                total(0,i2);
            }
            dr.Close();
            cn.Close();
        }

        private int total(int i,int i2)
        {
            int Total = i + i2;
            string total = Total.ToString();
            lblTotal.Text = total;

Answer 1

您需要从方法中返回一些内容：

private int total(int i,int i2)
{
    int Total = i + i2;
    return Total;
}

和

中的设置

private void cbService2_SelectedIndexChanged(object sender, EventArgs e)
{
    // your other code
    lblTotal.Text = total(i1, i2).ToString();
}

或者，如果您想要从方法中更改标签而不返回任何内容，请将其更改为

private void total (int i1, int i2)

Answer 2

在两个事件上都尊重地编辑代码。

lblService1.Text = dr["Amount"].ToString();
int i1 = Convert.ToInt32(lblService1.Text);
int i2 = Convert.ToInt32(lblService2.Text);
total(i1,i2);

lblService2.Text = dr["Amount"].ToString();
int i1 = Convert.ToInt32(lblService1.Text);
int i2 = Convert.ToInt32(lblService2.Text);
total(i1,i2);

SQL SUM（）函数也是一个很好的尝试。

需要计算两个整数值的总和

2 个答案: