StartIndex 不能小于零。参数名称：startIndex 使用 HijriDatePicker？

Question

我正在使用带有 gridview 控件的 Hijri Gregorian Datepicker 的许多实例，当我从 gridview 中删除时，我收到以下错误：

StartIndex cannot be less than zero.
Parameter name: startIndex

Line 173:                    //to manage multiple instances of user control postback, incase the postback happend due to culture changeed in current control,
Line 174:                    //the other user contrls culture drop down list to be changed accordingly. Also year and month dropdown lists according to culture 
Line 175:                    if (strPostBackControlName != "" && strPostBackControlName.Substring(strPostBackControlName.LastIndexOf("$")) == "$ddlLocaleChoice")
Line 176:                    {
Line 177:                        if (ddlLocaleChoice.SelectedValue == arabicCulture.Name)


[ArgumentOutOfRangeException: StartIndex cannot be less than zero.
Parameter name: startIndex]
   System.String.Substring(Int32 startIndex, Int32 length) +13011515
   System.String.Substring(Int32 startIndex) +15
   Hijri_Greg_DatePicker_Sample.HijriGregDatePicker.Page_Load(Object sender, EventArgs e) in C:\Users\Mawni\Desktop\Hijri_Greg_DatePicker_Sample\HijriGregDatePicker.ascx.cs:175
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +51
   System.Web.UI.Control.OnLoad(EventArgs e) +95
   System.Web.UI.Control.LoadRecursive() +59
   System.Web.UI.Control.LoadRecursive() +131
   System.Web.UI.Control.LoadRecursive() +131
   System.Web.UI.Control.LoadRecursive() +131
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +678

有帮助吗？

Answer 1

看这段代码：

strPostBackControlName.LastIndexOf("$")

它将 return 字符串中 $ 的最后一个索引，但是当未找到 $ 时，它将 return -1 作为结果。稍后您将尝试使用此结果调用 strPostBackControlName.Substring，但 Substring 具有以下原型：

public string Substring (int startIndex);

当然不能用小于 0 的起始索引调用它（因为字符串中的索引从 0 开始）。添加检查 LastIndexOf("$") 不是 -1 或确保 strPostBackControlName 始终包含 $。

StartIndex 不能小于零。参数名称：startIndex 使用 HijriDatePicker？

StartIndex cannot be less than zero. Parameter name: startIndex Using HijriDatePicker?

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