怎么取+之后和-之后的数。本人这段代码该怎么样改

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace eye4
{
    public partial class Form3 : Form
    {
        public Form3()
        {
            InitializeComponent();
        }
        private void Form3_Load(object sender, EventArgs e)
        {
            string sql = "select * from pinpai";
            DataSet ds = DBHelper.getset(sql);
            this.comboBox1.DisplayMember = "NAME";
            this.comboBox1.ValueMember = "NAME";
            DataTable dt = ds.Tables[0];
            this.comboBox1.DataSource = dt;
        }
        public string sql { get; set; }
        private void query()
        {
            sql = "select * from text1";
            DataTable dt1 = DBHelper.getset(sql).Tables[0];
            sql = "select * from text2";
            DataTable dt2 = DBHelper.getset(sql).Tables[0];
            sql = "select pinpai.NAME,AA_Inventory.name,ST_CurrentStock.baseQuantity,"" as a,"" as b  " +
                " from pinpai left join AA_Inventory on pinpai.id = AA_Inventory.productInfo " +
                " left join ST_CurrentStock on ST_CurrentStock.idinventory = AA_Inventory.id where  pinpai.NAME="1.56阳光快车混合散光"";
            DataTable dt3 = DBHelper.getset(sql).Tables[0];
            foreach (DataRow dr in dt3.Rows)
            {
                int iindex1 = dr["name1"].ToString().IndexOf("-", 0);
                int iindex2 = dr["name1"].ToString().IndexOf("-", iindex1 + 1);
                if (iindex1 > 0)
                {
                    string a = "";
                    string b = "";
                    if (iindex2 > 0)
                    {
                        a = dr["name1"].ToString().Substring(iindex1 + 1, iindex2 - iindex1 - 1);
                        b = dr["name1"].ToString().Substring(iindex2 + 1, dr["name1"].ToString().Trim().Length - iindex2 - 1);
                    }
                    else if (iindex2 == -1)
                    {
                        a = dr["name1"].ToString().Substring(iindex1 + 1);
                        b = "0";
                    }
                    dr["a"] = Convert.ToDecimal(a);
                    dr["b"] = Convert.ToDecimal(b);
                }
                // string a =dr["name1"].ToString ().Trim ().Substring ( dr["name1"].ToString().IndexOf("-", 0);
            }
            DataTable dt = new DataTable();
            dt.Columns.Add("球镜柱镜", typeof(System.String));
            foreach (DataRow dr in dt1.Rows)
            {
                dt.Columns.Add(dr["value"].ToString().Trim(), typeof(System.Double));
            }
            foreach (DataRow dr in dt2.Rows)
            {
                DataRow dradd = dt.NewRow();
                dradd["球镜柱镜"] = dr["value"];
                dt.Rows.Add(dradd);
            }
            this.dataGridView1.DataSource = dt;
            foreach (DataRow dr in dt3.Rows)
            {
                foreach (DataRow dr1 in dt.Rows)
                {
                    if (dr["a"].ToString().Trim() == dr1["球镜柱镜"].ToString().Trim())
                    {
                        dr1[dr["b"].ToString().Trim()] = dr["baseQuantity"];
                    }
                }
            }
        }
        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
        }
        private void button1_Click(object sender, EventArgs e)
        {
            query();
        }
    }
}