长度不能小于零。参数名称：长度 [英] Length cannot be less than zero. Parameter name: length

问题描述

protected void asd_Click(object sender, EventArgs e)
        {
            if (Common.Common.ApplicationInformation.LoggedInUser.RGroupIds != null)
            {
                string Documentid = string.Empty;
                string GroupIds = string.Empty;
                string DocumentIds = string.Empty;
                string ContactIds = string.Empty;
                //----------------
                if (Session["ReportDocumentIDs"].ToString() != null)
                {
                    DocumentIds = Session["ReportDocumentIDs"].ToString();
                    Documentid = DocumentIds.Substring(0, DocumentIds.LastIndexOf(','));
                }
                else
                {
                    Documentid = null;
                }

推荐答案

请阅读文档 [ ^ ]。这是因为

Please read the documentation[^]. It happens because

MSDN写道：

String.LastIndexOf 方法报告从零开始的索引位置此实例中最后一次出现的指定Unicode字符或字符串。 如果在此实例中找不到字符或字符串，则该方法返回-1。

String.LastIndexOf method reports the zero-based index position of the last occurrence of a specified Unicode character or string within this instance. The method returns -1 if the character or string is not found in this instance.

所以，你不能返回以零开头并以-1结尾的子串;）

So, you can not return substring which starts with zero and ends with -1 ;)

长度不能小于零。



Documentid = DocumentIds.Substring（0，DocumentIds.LastIndexOf（'，'））;



如果你传递的文件没有'，';



DocumentIds.LastIndexOf（'，'）这将返回-1;



然后Documentid = DocumentIds.Substring（0，-1）;抛出异常..





尝试处理它..如果您需要更多帮助，请告诉我..

Length cannot be less than zero.

Documentid = DocumentIds.Substring(0, DocumentIds.LastIndexOf(','));

This exception will occur if you are passing a DocumentIds without a ',' ;

DocumentIds.LastIndexOf(',') this will return -1;

then Documentid = DocumentIds.Substring(0, -1); throws exception..


Try to handle it..If you need more help let me know..

这篇关于长度不能小于零。参数名称：长度的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！