調用TextBox的KeyPress事件
private void txtUserId_KeyPress(object sender, KeyPressEventArgs e)
{
//如果輸入的不是數字鍵，也不是回車鍵、Backspace鍵，則取消該輸入
if (!(Char.IsNumber(e.KeyChar)) && e.KeyChar!=(char)13 && e.KeyChar!=(char)8)
{
e.Handled = true;
}
}
擴展資料：
註意事項
C#文本框輸入限制
//只能輸入數字和小數點和退格鍵
private void txt_KeyPress(object sender, KeyPressEventArgs e)
{
if (((int)e.KeyChar < 48 || (int)e.KeyChar > 57) && (int)e.KeyChar != 8 && (int)e.KeyChar != 46)
{
e.Handled = true;
}
}
//只能輸入數字和退格鍵
private void txt_KeyPress(object sender, KeyPressEventArgs e)
{
if (!(Char.IsNumber(e.KeyChar)) && e.KeyChar != (char)8)
{
e.Handled = true;
}
}
//限制輸入只能為數字
private void txt_KeyPress(object sender, KeyPressEventArgs e)
{
if (!(Char.IsNumber(e.KeyChar)) && e.KeyChar != (Char)8)
{
e.Handled = true;
}
}
//限制輸入不能為中文和全角
private void txt_KeyPress(object sender, KeyPressEventArgs e)
{
int chfrom = Convert.ToInt32("4e00", 16); //範圍（0x4e00～0x9fa5）轉換成int（chfrom～chend）
int chend = Convert.ToInt32("9fa5", 16);
if (e.KeyChar >= (Char)chfrom && e.KeyChar <= (Char)chend)
{
e.Handled = true;
}
if (e.KeyChar >= (Char)65281 & (int)e.KeyChar <= (Char)65374)
{
e.Handled = true;
}
}
//限制輸入只能輸入數字和字母，退格鍵
private void txt_KeyPress(object sender, KeyPressEventArgs e)
{
if ((e.KeyChar >= 'a' && e.KeyChar <= 'z') || (e.KeyChar >= 'A' && e.KeyChar <= 'Z')
|| (e.KeyChar >= '0' && e.KeyChar <= '9') || (e.KeyChar == 8))
{
e.Handled = false;
}
else
{
e.Handled = true;
}
}