难道是我的Ｒｐ有问题，关于ＩＦ（）

Question

private void button1_Click(object sender, EventArgs e)
        {
            string writestr = "";
            writestr = this.textBox1.Text.ToString();            if(this.textBox1.Text !="")
            {
                try
                {
                    IPAddress.Parse(writestr);                    if (File.Exists("severIP.txt"))
                    {
                        File.WriteAllText("severIP.txt", writestr);
                        MessageBox.Show("设置完成");
                    }
                    else
                    {
                        File.Create("severIP.txt");
                        File.WriteAllText("severIP.txt", writestr);
                        MessageBox.Show("设置完成");
                    }
                }
                catch (FormatException)
                {
                    MessageBox.Show("请输入正确的ＩＰ地址格式！");
                    this.textBox1.Clear();
                }
            }
            else
            {
                MessageBox.Show("请先输入服务器的ＩＰ地址");
            }        }
编译没有错误，但是最外面的这个ｉｆ并不进行判断，设断点监视，无效的表达式项ｉｆ
这是为什么，我搞了半天也没找到有错的地方，这个窗体里就只写了这些，应当不是其它地方的问题吧，求解，
急急急～　在线～

Answer 1

if(this.textBox1.Text.trim().lenth>0)

Answer 2

private void button1_Click(object sender, EventArgs e)
        {
            string writestr = string.Empty;
            writestr = this.textBox1.Text;            if(this.textBox1.Text.Trim().Length!=0)
            {
                try
                {
                    IPAddress.Parse(writestr);                    if (File.Exists("severIP.txt"))
                    {
                        File.WriteAllText("severIP.txt", writestr);
                        MessageBox.Show("设置完成");
                    }
                    else
                    {
                        File.Create("severIP.txt");
                        File.WriteAllText("severIP.txt", writestr);
                        MessageBox.Show("设置完成");
                    }
                }
                catch (FormatException)
                {
                    MessageBox.Show("请输入正确的ＩＰ地址格式！");
                    this.textBox1.Text="";
                }
            }
            else
            {
                MessageBox.Show("请先输入服务器的ＩＰ地址");
            }
        }
帮你改过一些，你复制后调试一下看看

Answer 3

这个问题是解决了，才发现，不能判断格式。 try
                {
                    IPAddress.Parse(writestr);                    if (File.Exists("severIP.txt"))
                    {
                        File.WriteAllText("severIP.txt", writestr);
                        MessageBox.Show("设置完成");
                    }
                    else
                    {
                        File.Create("severIP.txt");
                        File.WriteAllText("severIP.txt", writestr);
                        MessageBox.Show("设置完成");
                    }
                }
                catch (FormatException)
                {
                    MessageBox.Show("请输入正确的ＩＰ地址格式！");
                    this.textBox1.Clear();
                }
这里的IPAddress.Parse(writestr);不能进行判断么？

Answer 4

你看看IPAddress.Parse(writestr)这个返回值啊 我记得它返回的是个ip地址 怎么判断啊
又不是bool