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[英]How can I get a regex to check that a string only contains alpha characters [a-z] or [A-Z]?
[英]How to make a textbox only accep a-z and nothing else?
我在Windows窗体上有4个文本框。 我想将其更改为仅接受字母a到z的字母,而不是其他内容,即使粘贴内容也是如此。如果用户粘贴了字母和不需要的字符混合,则只有字母应显示在文本框中。
我想要的最后一件事是numlock pad。 这些数字与键盘顶部的数字行相同,但我也想让它们阻止它们!
我很确定应该有一些看起来像的语法; var isAlpha = char.IsLetter('text');
您需要做的就是在文本框中实现语法,如图所示; var isAlpha = textbox.char.IsLetter('text');
在ASCII表中,az的格式为97到122:
string str = "a string with some CAP letters and 123numbers";
void Start(){
string result = KeepaToz(str);
Debug.Log(result); // print "astringwithsomelettersandnumbers"
}
string KeepaToz(string input){
StringBuilder sb = new StringBuilder();
foreach(char c in str){
if(c >= 97 && c<= 122){ sb.Append(c); }
}
return sb.ToString();
}
我想通过类比这篇文章来介绍一个从TextBox
派生的自定义控件:
public class LettersTextBox : TextBox
{
protected override void OnKeyPress(KeyPressEventArgs e)
{
base.OnKeyPress(e);
string c = e.KeyChar.ToString();
if (e.KeyChar >= 'a' && e.KeyChar <= 'z' || char.IsControl(e.KeyChar))
return;
e.Handled = true;
}
protected override void WndProc(ref System.Windows.Forms.Message m)
{
const int WM_PASTE = 0x0302;
if (m.Msg == WM_PASTE)
{
string text = Clipboard.GetText();
if (string.IsNullOrEmpty(text))
return;
if (text.Any(c => c < 'a' || c > 'z'))
{
if (text.Any(c => c >= 'a' || c <= 'z'))
SelectedText = new string(text.Where(c => c >= 'a' && c <= 'z').ToArray());
return;
}
}
base.WndProc(ref m);
}
}
使用TextChanged
事件。 就像是:
// Set which characters you allow here
private bool IsCharAllowed(char c)
{
return (c >= 'a' && c <= 'z')
}
private bool _parsingText = false;
private void textBox1_TextChanged(object sender, EventArgs e)
{
// if we changed the text from within this event, don't do anything
if(_parsingText) return;
var textBox = sender as TextBox;
if(textBox == null) return;
// if the string contains any not allowed characters
if(textBox.Text.Any(x => !IsCharAllowed(x))
{
// make sure we don't reenter this when changing the textbox's text
_parsingText = true;
// create a new string with only the allowed chars
textBox.Text = new string(textBox.Text.Where(IsCharAllowed).ToArray());
_parsingText = false;
}
}
您可以将此方法分配给每个文本框TextChanged
事件,并且它们只允许它们输入IsCharAllowed()
(如果通过粘贴,通过键入,触摸屏或其他方式无关紧要)
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