private void tb_KeyPress(object sender, KeyPressEventArgs e)
{
    //如果输入的不是退格和数字，则屏蔽输入
    if (!(e.KeyChar == ‘\b‘ || (e.KeyChar >= ‘0‘ && e.KeyChar <= ‘9‘)))
    {
        e.Handled = true;
    }
}

private void tb_KeyPress(object sender, KeyPressEventArgs e)
{
    //如果输入的不是退格和数字，则屏蔽输入
    if (!(e.KeyChar == 8 || (e.KeyChar >= 48 && e.KeyChar <= 57)))
    {
        e.Handled = true;
    }
}

private void tb_KeyPress(object sender, KeyPressEventArgs e)
{
    //如果输入的不是退格和十进制数字，则屏蔽输入
    if (!(e.KeyChar == ‘\b‘ || char.IsDigit(e.KeyChar)))
    {
        e.Handled = true;
    }
}

private void tb_KeyPress(object sender, KeyPressEventArgs e)
{
    //如果输入的不是退格且不能转为整数，则屏蔽输入
    if (!(e.KeyChar == ‘\b‘ || int.TryParse(((TextBox)sender).Text + e.KeyChar.ToString(), out int i)))
    {
        e.Handled = true;
    }
}

private void tb_KeyPress(object sender, KeyPressEventArgs e)
{
    //当前输入的是"."且(输入框已经有“.”或者文本框没有内容)，则屏蔽输入
    if (e.KeyChar == ‘.‘ && (((TextBox)sender).Text.IndexOf(".") != -1 || ((TextBox)sender).Text.Length == 0))
    {
        e.Handled = true;
    }
    //如果输入的不是退格、数字和点，则屏蔽输入
    if (!(e.KeyChar == ‘\b‘ || (e.KeyChar >= ‘0‘ && e.KeyChar <= ‘9‘) || e.KeyChar == ‘.‘))
    {
        e.Handled = true;
    }
}

private void tb_KeyPress(object sender, KeyPressEventArgs e)
{
    //如果输入的不是退格且不能转为小数，则屏蔽输入
    if (!(e.KeyChar == ‘\b‘ || float.TryParse(((TextBox)sender).Text + e.KeyChar.ToString(), out float f)))
    {
        e.Handled = true;
    }
}

private void tb_KeyPress(object sender, KeyPressEventArgs e)
{
    //如果输入的不是负号，退格且不能转为小数，则屏蔽输入
    if (!(e.KeyChar == ‘-‘|| e.KeyChar == ‘\b‘ || float.TryParse(((TextBox)sender).Text + e.KeyChar.ToString(), out float f)))
    {
        e.Handled = true;
    }
}