listbox的运用

//添加一个系统用户
protected void btn_insertSystemUser_Click(object sender, EventArgs e)
{
ListItem li = new ListItem();
if (lb_systemUser.Items.Count == 0)
{
li.Text = txt_loginName.Text.Trim();
li.Value = txt_password.Text;
lb_systemUser.Items.Add(li);
}
else
{
int result = 0;
for (int i = 0; i < lb_systemUser.Items.Count; i++)
{
if (txt_loginName.Text.Trim() == lb_systemUser.Items[i].Text)
{
ScriptManager.RegisterStartupScript(this, GetType(), "", " document.getElementById(/"table_systemUser/").style.display = /"block/";alert('此项用户已存在，请重新添加一位！');", true);
txt_loginName.Focus();
break;
}
else
{
result++;
}
}
if (result == lb_systemUser.Items.Count)
{
li.Text = txt_loginName.Text.Trim();
li.Value = txt_password.Text;
lb_systemUser.Items.Add(li);
}
}
up_systemUser.Update();
ScriptManager.RegisterStartupScript(this, GetType(), "", " document.getElementById(/"table_systemUser/").style.display = /"block/";", true);
}

//移除
protected void btn_remove_Click(object sender, EventArgs e)
{
if (lb_systemUser.SelectedIndex != -1)
{
if (lb_systemUser.Items[lb_systemUser.SelectedIndex].Selected)
{
lb_systemUser.Items.RemoveAt(lb_systemUser.SelectedIndex);
up_systemUser.Update();
ScriptManager.RegisterStartupScript(this, GetType(), "", " document.getElementById(/"table_systemUser/").style.display = /"block/";", true);
}
}
else
{
ScriptManager.RegisterStartupScript(this, GetType(), "", " document.getElementById(/"table_systemUser/").style.display = /"block/";alert('请选择一项进行移除！')", true);
}
}

循环添加listbox里的值

if (lb_systemUser.Items.Count == 0)
{
lbl_loginAccount.Text = "无";
}
else
{
string authorizaionName = "";
for (int i = 0; i < lb_systemUser.Items.Count; i++)
{
authorizaionName += lb_systemUser.Items[i].Text + " ";
}
lbl_loginAccount.Text = authorizaionName;
}