How to Find Any Character in Text

Now I know how to count the number of characters in the entire input text, using the TextChanged event, using charCount=input.Text.Length.

Then, what should I do to find out how many characters are in the input text?
*Both characters (search words, text to be searched) will be entered in the text box.

Example
Input text → December is a busy month ahead of Christmas and New Year's Day.
Input search word → month

Results are 3 characters

c# wpf

2022-09-30 21:34

3 Answers

For example:

string target="December is a busy month ahead of Christmas and New Year's Day.";
string find = "month";
int count = 0;

int index=target.IndexOf(find, StringComparison.Order);
while (0<=index)
{
    count++;
    index=target.IndexOf(find, index+1, StringComparison.Order);
}
// count = 3

Repeat looking for the string from the beginning, add count 1 to count, and look for the next string.

2022-09-30 21:34

Total length of string - length of string with destination deleted = number of destination characters

str.Length-str.Replace(chara.ToString(), "").Length;

2022-09-30 21:34

WPF provides a wealth of binding capabilities.

converter allows you to code the conversion logic.You can also express counting actions like questions: Implement IValueConverter.
MultiBinding allows you to bind multiple values.You can bind the input text and the input search word.
In this case, implement IMultiValueConverter as the converter.
Binding has StringFormat and can be formatted.

Other people answered how to count characters, but you can also use the number that matches the regular expression.To sum up, define a CountConverter implementing IMultiValueConverter.

public class CountConverter:IMultiValueConverter{
    static int Count (string input, string pattern)
        =>Regex.Matches(input,Regex.Escape(pattern)) .Count;
    public object Convert (object[] values, Type targetType, object parameter, CultureInfoculture)
        =>Count(string) values[0], (string) values[1]);
    public object [ ] ConvertBack (object value, Type [ ] targetTypes, object parameter, CultureInfoculture)
        =>throw new NotImplementedException();
}

The XAML side has registered a converter in the resource dictionary.

<Window.Resources>
    <local:CountConverter x:Key="CountConverter"/>
</ Window.Resources>

Then prepare and bind TextBox and TextBlock.

<TextBoxName="source"Text="December is a busy month ahead of Christmas and New Year's Day." HorizontalAlignment="Left" Height="23" Margin="28,29,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="300"/>
<TextBox Name="template" Text="Month" HorizontalAlignment="Left" Height="23" Margin="28,57,0,0"TextWrapping="Wrap" VerticalAlignment="Top" Width="120"/gt;
<TextBlock HorizontalAlignment="Left" Margin="28,85,0,0"TextWrapping="Wrap" VerticalAlignment="Top">
    <TextBlock.Text>
        <MultiBinding Converter="{StaticResource CountConverter}"StringFormat="Results are {0} characters">
            <Binding ElementName="source"Path="Text"/>
            <Binding ElementName="template" Path="Text"/>
        </MultiBinding>
    </TextBlock.Text>
</TextBlock>

Of course, it's a bind, so editing characters reflects results almost in real time.

2022-09-30 21:34

If you have any answers or tips

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