WPF stringformat show only digital - wpf

Question

i want in wpf application show only decimal number in a textblock.
I have for example "35.56", i want show only ".56"
Thank you

Answer 1

You can represent 0.56 as only .56 using <TextBlock Text="{Binding Path=yourprop, StringFormat='#.##'}" /> but 35.56 cannot be represented using .56 using a StringFormat because 35.56 and .56 are two different values.
If you want to represent 35.56 as .56 for some strange reason, you'd better format the string using some custom logic in your view model:
public string YourPropFormatted
{
get
{
string s = yourprop.ToString("#.00", CultureInfo.InvariantCulture);
int index = s.IndexOf('.');
return (index > 0) ? s.Substring(index) : s;
}
}
XAML is a markup language and can't handle this.

Answer 2

Complementing mm8 answer with another way to get the same result is implementing a IValueConverter.
public class NumberToDecimalPartConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if(!(value is double val))
return default(double).ToString(); // or ".00", you decide
string s = val.ToString("#.00", CultureInfo.InvariantCulture);
int index = s.IndexOf('.');
return index > 0 ? s.Substring(index) : s;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
// you don't need convert back
throw new NotImplementedException();
}
}
Assuming the converter is placed at same namespace
<Window.Resources>
<local:NumberToDecimalPartConverter x:Key="NumberToDecimalPart"/>
</Window.Resources>
<TextBlock Text="{Binding Path=yourprop, Converter={StaticResource NumberToDecimalPart}}" />
When your property changes, the UI will be updated, right?
With converter, you have one more step that is convert the value.
So what I'm doing here it's when the property (your probably double value) change, the WPF will call the Convert function from NumberToDecimalPartConverter. When the property have Mode setted as TwoWay will call ConvertBack.