使用 C# 函数检查空文本框

问题描述

我编写了一个函数来检查表单上的任何文本框是否为空白.如果我将它添加到 TextBox 'leave' 事件，它目前可以工作.

I have written a function to check if any textboxes on a form are blank.It currently works if I add it to the TextBox 'leave' event.

我尝试将其添加到按钮点击事件中，但出现错误(NullReferenceException unhandled).

I tried adding it to a button click event but it gives an error (NullReferenceException unhandled).

代码如下:

public void inputBlank(object sender, EventArgs e)
    {
        TextBox userInput;
        userInput = sender as TextBox;
        userTextBox = userInput.Text;
        string blankBoxName = userInput.Name;
        string blankBox = blankBoxName.Remove(0,3);

        if (userTextBox == "")
        {
            errWarning.SetError(userInput, "Please enter a value for " + blankBox);
            userInput.Focus();
        }
        else
        {
            errWarning.SetError(userInput, "");
        }
    }

只是想知道您是否可以建议我如何修复它.

Just wondering if you could advise me how to fix it.

非常感谢.

推荐答案

您想验证 Windows 应用程序中的空文本框吗?最好在验证/验证事件中使用它.

You want to validate an empty textbox in Windows application? Better to use it in Validating / Validate event.

private void sampleTextbox8_Validating(object sender, CancelEventArgs e)
{
    TextBox textbox = sender as TextBox;
    e.Cancel = string.IsNullOrWhiteSpace(textbox.Text);
    errorProvider1.SetError(textbox, "String cannot be empty");
}

private void sampleTextbox8_Validated(object sender, EventArgs e)
{
    TextBox textbox = sender as TextBox;
    errorProvider1.SetError(textbox, string.Empty);
}

这些链接可能对您有所帮助

These links may help you

1. 验证 WinForms TextBox(在 C# 中)
2. WinForm UI 验证

这篇关于使用 C# 函数检查空文本框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！