无法从 TextChanged 事件处理程序引用文本框的文本属性 [英] Can't refer to Text propery of textbox from TextChanged eventhandler

问题描述

我在 TextChanged 事件处理程序中获取文本框的 Text 值时遇到问题.

I have a problem with getting the Text value of a textbox in the TextChanged event handler.

我有以下代码.(简化)

I have the following code. (simplified)

public float varfloat;

private void CreateForm()
{
    TextBox textbox1 = new TextBox();
        textbox1.Location = new Point(67, 17);
        textbox1.Text = "12.75";
        textbox1.TextChanged +=new EventHandler(textbox1_TextChanged);
}

private void textbox1_TextChanged(object sender, EventArgs e)
    {
         varfloat = float.Parse(textbox1.Text);
    }

我收到以下错误:当前上下文中不存在名称 textbox1".

I get the following error:'the name textbox1 does not exist in the current context'.

我可能在某个地方犯了一个愚蠢的错误，但我是 C# 新手，希望得到一些帮助.

I probably made a stupid mistake somewhere, but I'm new to C# and would appreciate some help.

提前致谢！

推荐答案

您已在 CreateForm 中将 textBox1 声明为 局部变量.变量只存在于该方法中.

You've declared textBox1 as a local variable within CreateForm. The variable only exists within that method.

三个简单的选项:

• 使用 lambda 表达式在 CreateForm 中创建事件处理程序 :

• Use a lambda expression to create the event handler within CreateForm:

private void CreateForm()
{
    TextBox textbox1 = new TextBox();
    textbox1.Location = new Point(67, 17);
    textbox1.Text = "12.75";
    textbox1.TextChanged += 
        (sender, args) => varfloat = float.Parse(textbox1.Text);
}

将 sender 转换为 Control 并改用它:

Cast sender to Control and use that instead:

private void textbox1_TextChanged(object sender, EventArgs e)
{
    Control senderControl = (Control) sender;
    varfloat = float.Parse(senderControl.Text);
}

将 textbox1 改为实例变量.如果您想在代码中的任何其他地方使用它，这将很有意义.

Change textbox1 to be an instance variable instead. This would make a lot of sense if you wanted to use it anywhere else in your code.

哦，请不要使用公共字段:)

Oh, and please don't use public fields :)

这篇关于无法从 TextChanged 事件处理程序引用文本框的文本属性的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！