索引和长度必须引用该字符串内的位置。参数名: length

public partial class manage_editnews : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["username"] == null)
        {
            Response.Redirect("~/login.aspx");
        }
        if (!IsPostBack)
        {
            band();
            bindgrid();
        }
    }
    private void band()//---绑定dripdownlist控件数据，用于绑定新闻类型
    {
        SqlConnection con = conn.createconn();
        con.Open();
        string aa = "select typename from newstype";
        SqlDataAdapter sda = new SqlDataAdapter();
        sda.SelectCommand = new SqlCommand(aa, con);
        DataSet ds = new DataSet();
        sda.Fill(ds);
        this.droptype.DataSource = ds;//绑定dripdownlist
        this.droptype.DataTextField = "typename";
        this.droptype.DataValueField = "typename";
        this.droptype.DataBind();

    }
    private void bindgrid()
    {
        SqlConnection con = conn.createconn();//---绑定GridView1控件数据，用于绑定新闻类型
        con.Open();
        string aa = "select adid, adname, adsubject, adtype, adcontent, adhit, addata from news";
        SqlDataAdapter sda = new SqlDataAdapter();
        sda.SelectCommand = new SqlCommand(aa, con);
        DataSet ds = new DataSet();
        sda.Fill(ds);
        this.GridView1.DataSource = ds;
        this.GridView1.DataBind();
        con.Close();
    }

    public string GetContent(string str)
    {
        int i = str.Length;
         string substr =str.Substring(0,5)+"....";
//在这里出错：用户代码未处理ArgumentOutOfRangeException        return substr ;
    }

    protected void btnedit_Click1(object sender, EventArgs e)
    {
        if(Convert.ToInt32(ViewState["adid"])==0)
        {
            Response.Write("<script>alert('你还没有选择要更新的数据！');</script>");
        }
        else
        {
            SqlConnection con = conn.createconn();
            con.Open();
            int aa = Convert.ToInt32(ViewState["adid"]);
            string str = "select adid,adsubject,adtype,adcontent from news where adid=" + aa + " ";
            SqlCommand cmd = new SqlCommand(str, con);
            SqlDataReader rd = cmd.ExecuteReader();
            if (rd.Read())
            {
                tsubject.Text = rd["adsubject"].ToString();
                tcontent.Text = rd["adcontent"].ToString();
                this.droptype.Text = rd["adtype"].ToString();
            }
            con.Close();
            this.p1.Visible = true;
            this.p2.Visible = false;
        }

    }

    protected void btneditnew_Click(object sender, EventArgs e)
    {
            if (15 > Length(this.tcontent.Text))
            {
                Response.Write("<script>alert('新闻内容不能少于15个字符！');</script>");
            }
            else
            {
                SqlConnection con = conn.createconn();
                con.Open();

                int aa = Convert.ToInt32(ViewState["adid"]);
                string str = "update news set adsubject = '" + this.tsubject.Text + "' ,adcontent= '" + tcontent.Text + "',adtype='" + this.droptype.SelectedValue + "',addata='" + DateTime.Now +"' where adid=" + aa + "";
                SqlCommand cmd = new SqlCommand(str, con);
                cmd.ExecuteNonQuery();
                con.Close();
                bindgrid();
                Response.Write("<script>alert('更新成功！');</script>");
                this.p2.Visible = true;
                this.p1.Visible = false;
            }
    }
    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {
        int aa = Convert.ToInt32(this.GridView1.SelectedRow.Cells[0].Text);
        ViewState["adid"] = aa;

    }
    protected void btndelt_Click1(object sender, EventArgs e)
    {
        if (Convert.ToInt32(ViewState["adid"]) == 0)
        {
            Response.Write("<script>alert('你还没有选择要删除的数据！');</script>");
        }
        else
        {
            btndelt.Attributes.Add("onClick", "javascript:return   confirm('确定删除吗？');");
            //Response.write("<script>return confirm('是否要删除此记录')</script>");
            SqlConnection con = conn.createconn();
            con.Open();
            // string str = "delete from news where adid=" + Convert.ToInt32(DataGrid1.SelectedItem.Cells[0].Text) + " ";
            int aa = Convert.ToInt32(ViewState["adid"]);
            string str = "delete from news where adid=" + aa + "";
            SqlCommand cmd = new SqlCommand(str, con);
            cmd.ExecuteNonQuery();
            con.Close();
            bindgrid();
        }
    }

    protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        this.GridView1.PageIndex = e.NewPageIndex;
        bindgrid();

    }
    protected void btncannle_Click(object sender, EventArgs e)
    {
        this.p2.Visible = true;
        this.p1.Visible = false;
    }
    public int Length(string str)
    {
        int length = str.Length;
        //用户验证控件
        Regex RegCHZN = new Regex("[\u4e00-\u9fa5]");
        foreach (char c in str)
        {
            Match m = RegCHZN.Match(c.ToString());
            if (m.Success)
            {
                length++;
            }
        }
        return length;
    }
}

7 个解决方案

#1

string substr =str.Substring(0,5)+"....";
//在这里出错：用户代码未处理ArgumentOutOfRangeException
"索引和长度必须引用该字符串内的位置。参数名: length“ 为什么出现这个错误，请教高手!

#2

int i = str.Length;
if(i>=5) string substr =str.Substring(0,5)+"....";

#3

  public string GetContent(string str)
        {
            string substr = string.Empty;
            int i = str.Length;
            if (!string.IsNullOrEmpty(str))
            {
                if (i > 5)
                {
                    substr = str.Substring(0, 5) + "....";
                }
                else
                {
                    substr = str;
                }
            }
            return substr ;
        }

#4

public string GetContent(string str)
{
　int i = str.Length;
　string substr = str;
　if(i > 5)
　{
　　string substr =str.Substring(0,5)+"....";
　}
　return substr;
}

#5

str的长度少于你的str.Substring(0,5),所以要报错.你的str长度必须>=5,Substring才不会报错

#6

。。。。连 index 越界都搞不定么？ 5 > Length 啦

#7

引用 3 楼 return_false 的回复:

C# code

  public string GetContent(string str)
        {
            string substr = string.Empty;
            int i = str.Length;
            if (!string.IsNullOrEmpty(str))
            {
  ……

问题解决了，谢谢！

#1

#2