Accept only one comma in Textbox c# WPF

Question

Hello I have my decimal textbox like this:

      <TextBox x:Name="TextBox"  KeyDown="TextBox_KeyDown"  
        Style="{StaticResource MeuTextBoxValor}" Height="23" Margin="1"   
        Text="{Binding Peso,  NotifyOnValidationError=true,  StringFormat={}{0:#0.00##}, 
    ConverterCulture='pt-BR', 
UpdateSourceTrigger=PropertyChanged}" 
VerticalAlignment="Center" Width="120" />

When you put a comma in this field it gets like this

0,00

And when he starts writing he writes like this

0,22,00

I’d like to take that "." off to the right. I’ve tried to give a TextBox.Text.Replace(",00","") but he continues to put.

Answer 1

It may be better to validate the value when entering text, to avoid incorrect input of characters.

For this you must subscribe to the event PreviewTextInput:

<TextBox PreviewTextInput="PreviewTextInput" />

In the method PreviewTextInput validate the comma:

private void TextBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
    bool approvedDecimalPoint = false;

    if (e.Text == ",")
    {
        if (!((TextBox)sender).Text.Contains(","))
            approvedDecimalPoint = true;
    }

    if (!(char.IsDigit(e.Text, e.Text.Length - 1) || approvedDecimalPoint))
        e.Handled = true;
}