About dynamically generating textbox and dynamically obtaining testbox values

mclstc

I use a dynamic way to automatically generate a lot of text boxes on the page
  for(int i = 1;i<100;i++)
  {
    TextBox t = new TextBox()
    t.ID = "a"+i.ToString();
    this.Page.Controls.Add(t);
  }

Use when getting
string b;
for (in i=1;i<=100;i++)
{
TextBox ck= (TextBox)this.FindControl("a"+i.ToString());
b=ck.text
}

There is an error when acquiring, and the value can be obtained when i=1 during the loop, and an error will occur when the loop continues
Unable to cast object of type'System.Web.UI.WebControls.DropDownList' to type'System.Web.UI.WebControls.TextBox'.

摩羯可乐

for(int i = 1;i<100;i++)

for (in i=1;i<=100;i++)
Are these two the same? Just check it carefully

mclstc

This is the wrong number when I came up
Specifically not because of this

zyzyzy22

Control tmp=this.FindControl("a"+i.ToString();
TextBox tmpTextBox=tmp is TextBox?(TextBox)tmp:null;
if (tmpTextBox != null)
{
...
}

mclstc

Thank you! Passed, can you explain? Why did mine just go wrong?

zyzyzy22

Unable to cast object of type'System.Web.UI.WebControls.DropDownList' to type'System.Web.UI.WebControls.TextBox'.
Isn't it said here?