只爲數字掩蓋文本框，但不會接受BackSpace

Question

我有一個文本框，我只想要數字。但是如果我輸錯了數字，我不能退格來糾正它。我怎樣才能讓後臺工作。由於

private void amount_PaidTextBox_KeyPress(object sender, KeyPressEventArgs e) 
    { 
     if (Char.IsNumber(e.KeyChar) != true) 
     { 
      e.Handled = true; 
     } 
    } 

Answer 1

你可以添加一個檢查，以便控制字符，以及：

if (Char.IsControl(e.KeyChar) != true && Char.IsNumber(e.KeyChar) != true) 
{ 
    e.Handled = true; 
} 

更新：響應於人-B的對代碼的評論/他暗示下面的風格（這也是我怎麼會親自寫）：

if (!Char.IsControl(e.KeyChar) && !Char.IsNumber(e.KeyChar)) 
{ 
    e.Handled = true; 
} 

Answer 2

private void amount_PaidTextBox_KeyPress(object sender, KeyPressEventArgs e) 
{ 
    if (!Char.IsNumber(e.KeyChar) && e.KeyCode != Keys.Back) 
      e.Handled = True; 
} 

Answer 3

一個稍微乾淨上面的格式：

private void amount_PaidTextBox_KeyPress(object sender, KeyPressEventArgs e) 
{ 
    e.Handled = !(Char.IsNumber(e.KeyChar) || (e.KeyChar==Keys.Back)); 
} 

Answer 4

您也可以覆蓋框TextChanged事件：

private void textBox1_TextChanged(object sender, EventArgs e) 
{ 
    string text = (sender as TextBox).Text; 

    StringBuilder builder = new StringBuilder(String.Empty); 

    foreach (char character in text) 
    { 
     if (Char.IsDigit(character)) 
     { 
      builder.Append(character); 
     } 
    } 

    (sender as TextBox).Text = builder.ToString(); 
} 

請注意，您必須在代碼添加到設置插入符位置。

Answer 5

正確答案是：

private void amount_PaidTextBox_KeyPress(object sender, KeyPressEventArgs e) 
{ 
    e.Handled = !сhar.IsNumber(e.KeyChar) && (e.KeyChar != '\b'); 
} 

Answer 6

我發現下面的效果很好。它包括允許退格鍵，方向鍵刪除鍵額外異常等 How to allow only numeric (0-9) in HTML inputbox using jQuery?

Answer 7

private void txt_KeyPress(object sender, KeyPressEventArgs e) 
{ 
    if (Char.IsDigit(e.KeyChar) || e.KeyChar == '\b') 
    { 
     // Allow Digits and BackSpace char 
    }   
    else 
    { 
     e.Handled = true; 
    } 
} 

參考鏈接也：Masking Textbox to accept only decimals小數/ 12209854＃12209854