写了个代码,出现如下错误,帮助解决一下,谢谢!
private void Board()
{
string Sqlc,Sqlb;
Sqlc="select * from [Class] where Isdel=0";
OleDbDataReader resultc=GetList(Sqlc);
dlfcList.DataSource=resultc;
dlfcList.DataBind();
resultc.Close();
for (int j=0;j<dlfcList.Items.Count;j++)
{
Label labClassName=(Label)dlfcList.Items[j].FindControl("labClassName");
Label labClassID=(Label)dlfcList.Items[j].FindControl("labClassID");
Sqlb="select * from [Board] where Isdel=0 or Hidden=0 and ClassID="+labClassID.Text;
OleDbDataReader resultb=GetList(Sqlb);
dlfbList.DataSource=resultb;
dlfbList.DataBind();
for (int i=0;i<dlfbList.Items.Count;i++)
{
Label labBoardName=(Label)dlfbList.Items[i].FindControl("labBoardName");
Label labReadme=(Label)dlfbList.Items[i].FindControl("labReadme");
Label labLastPostTitle=(Label)dlfbList.Items[i].FindControl("labLastPostTitle");
Label labLastPostUser=(Label)dlfbList.Items[i].FindControl("labLastPostUser");
Label labLastPostDate=(Label)dlfbList.Items[i].FindControl("labLastPostDate");
Label labAdmin=(Label)dlfbList.Items[i].FindControl("labAdmin");
Label labLastTodayNum=(Label)dlfbList.Items[i].FindControl("labLastTodayNum");
Label labLastbbsNum=(Label)dlfbList.Items[i].FindControl("labLastbbsNum");
Label labLastTopicNum=(Label)dlfbList.Items[i].FindControl("labLastTopicNum");未将对象引用设置到对象的实例。
说明: 执行当前 Web 请求期间,出现未处理的异常。请检查堆栈跟踪信息,以了解有关该错误以及代码中导致错误的出处的详细信息。 异常详细信息: System.NullReferenceException: 未将对象引用设置到对象的实例。源错误:
行 289: Sqlb="select * from [Board] where Isdel=0 or Hidden=0 and ClassID="+labClassID.Text;
行 290: OleDbDataReader resultb=GetList(Sqlb);
行 291: dlfbList.DataSource=resultb;
行 292: dlfbList.DataBind();
行 293: for (int i=0;i<dlfbList.Items.Count;i++)
源文件: f:\inetpub\wwwroot\zstudiocn\members\index.aspx.cs 行: 291
private void Board()
{
string Sqlc,Sqlb;
Sqlc="select * from [Class] where Isdel=0";
OleDbDataReader resultc=GetList(Sqlc);
dlfcList.DataSource=resultc;
dlfcList.DataBind();
resultc.Close();
for (int j=0;j<dlfcList.Items.Count;j++)
{
Label labClassName=(Label)dlfcList.Items[j].FindControl("labClassName");
Label labClassID=(Label)dlfcList.Items[j].FindControl("labClassID");
Sqlb="select * from [Board] where Isdel=0 or Hidden=0 and ClassID="+labClassID.Text;
OleDbDataReader resultb=GetList(Sqlb);
dlfbList.DataSource=resultb;
dlfbList.DataBind();
for (int i=0;i<dlfbList.Items.Count;i++)
{
Label labBoardName=(Label)dlfbList.Items[i].FindControl("labBoardName");
Label labReadme=(Label)dlfbList.Items[i].FindControl("labReadme");
Label labLastPostTitle=(Label)dlfbList.Items[i].FindControl("labLastPostTitle");
Label labLastPostUser=(Label)dlfbList.Items[i].FindControl("labLastPostUser");
Label labLastPostDate=(Label)dlfbList.Items[i].FindControl("labLastPostDate");
Label labAdmin=(Label)dlfbList.Items[i].FindControl("labAdmin");
Label labLastTodayNum=(Label)dlfbList.Items[i].FindControl("labLastTodayNum");
Label labLastbbsNum=(Label)dlfbList.Items[i].FindControl("labLastbbsNum");
Label labLastTopicNum=(Label)dlfbList.Items[i].FindControl("labLastTopicNum");未将对象引用设置到对象的实例。
说明: 执行当前 Web 请求期间,出现未处理的异常。请检查堆栈跟踪信息,以了解有关该错误以及代码中导致错误的出处的详细信息。 异常详细信息: System.NullReferenceException: 未将对象引用设置到对象的实例。源错误:
行 289: Sqlb="select * from [Board] where Isdel=0 or Hidden=0 and ClassID="+labClassID.Text;
行 290: OleDbDataReader resultb=GetList(Sqlb);
行 291: dlfbList.DataSource=resultb;
行 292: dlfbList.DataBind();
行 293: for (int i=0;i<dlfbList.Items.Count;i++)
源文件: f:\inetpub\wwwroot\zstudiocn\members\index.aspx.cs 行: 291
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private void Board()
{
string Sqlc,Sqlb;
Sqlc="select * from [Class] where Isdel=0";
OleDbDataReader resultc=GetList(Sqlc);
dlfcList.DataSource=resultc;
dlfcList.DataBind();
resultc.Close();
for (int j=0;j<dlfcList.Items.Count;j++)
{
Label labClassName=(Label)dlfcList.Items[j].FindControl("labClassName");
Label labClassID=(Label)dlfcList.Items[j].FindControl("labClassID");
Sqlb="select BoardName,Readme,LastPostTitle,LastPostUser,LastPostDate,Admin,LastTodayNum,LastbbsNum,LastTopicNum from [Board] where Isdel=0 or Hidden=0 and ClassID="+labClassID.Text;
DataList dlfbList=(DataList)dlfcList.Items[j].FindControl("dlfbList");
OleDbDataReader resultb=GetList(Sqlb);
dlfbList.DataSource=resultb;
dlfbList.DataBind();
for (int i=0;i<dlfbList.Items.Count;i++)
{
Label labBoardName=(Label)dlfbList.Items[i].FindControl("labBoardName");
Label labReadme=(Label)dlfbList.Items[i].FindControl("labReadme");
Label labLastPostTitle=(Label)dlfbList.Items[i].FindControl("labLastPostTitle");
Label labLastPostUser=(Label)dlfbList.Items[i].FindControl("labLastPostUser");
Label labLastPostDate=(Label)dlfbList.Items[i].FindControl("labLastPostDate");
Label labAdmin=(Label)dlfbList.Items[i].FindControl("labAdmin");
Label labLastTodayNum=(Label)dlfbList.Items[i].FindControl("labLastTodayNum");
Label labLastbbsNum=(Label)dlfbList.Items[i].FindControl("labLastbbsNum");
Label labLastTopicNum=(Label)dlfbList.Items[i].FindControl("labLastTopicNum");
}
resultb.Close();
} }为什么不能按分类显示,即循环嵌套,为何内层循环的循环次数不能根据上层内规定的次数,上层的次数的写法不对?