//文本框显示一个0
this.pageNavigation.toolStripTextBox1.Text = "0";

//这是该文本框text值改变时发生事件
void pageNavigation_TextChanged(object sender, EventArgs e)
{
    string pageCount= this.pageNavigation.toolStripTextBox1.Text.Trim();
    if (pageCount == "0" || pageCount == "")
    {
        this.pageNavigation.toolStripTextBox1.Text = "1";
    }
    else if (int.Parse(pageCount) > this.paging.PageNumber)  //this.paging.PageNumber值为0
    {
        this.pageNavigation.toolStripTextBox1.Text = this.paging.PageNumber.ToString();
    }
}

//这样写,这个事件会形成无限循环,请问要怎么改才好?

void pageNavigation_TextChanged(object sender, EventArgs e)
{
    string pageCount= this.pageNavigation.toolStripTextBox1.Text.Trim();
    if (pageCount == "0" || pageCount == "")
    {
        this.pageNavigation.toolStripTextBox1.Text = "1";
    }
    else(int.Parse(pageCount) > this.paging.PageNumber)  //this.paging.PageNumber值为0
    {
        this.pageNavigation.toolStripTextBox1.Text = this.paging.PageNumber.ToString();
    }
}

------解决方案--------------------
楼主是想让this.pageNavigation.toolStripTextBox1.Text 的值只能为0和1？？？

C# code

void pageNavigation_TextChanged(object sender, EventArgs e)
{
    string pageCount= this.pageNavigation.toolStripTextBox1.Text.Trim();
    if (pageCount == "0" || pageCount == "")
    {
        this.pageNavigation.toolStripTextBox1.Text = "1";
    }
    else(int.Parse(pageCount) > this.paging.PageNumber)  //this.paging.PageNumber值为0
    {
        this.pageNavigation.toolStripTextBox1.Text = this.paging.PageNumber.ToString();
    }
}