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c#regex
Hooman Bahreini
Hooman Bahreini

Reputation: 15559

Regex: Match everything until the last white space

I want to reduce the length of my input string to max 20 characters, but I don't want't to break the string in the middle of a word.

// show me 20 char:   12345678901234567890 
string inputString = "This is an example user input which has to be shorten at a white space";
if (inputString.length > 20)
{
    shortenString = inputString.SubString(0, 21); // <-- "This is an example us"
    
    // I need a regex to match everything until the last white space

    // final output: "This is an example"
}

Upvotes: 1

Views: 547

Answers (2)

Hooman Bahreini
Hooman Bahreini

Reputation: 15559

I used the RegEx from @Ced answer, this is the final extension method:

public static string ShortenStringAtWhiteSpaceIfTooLong(this string str, int maxLen)
{
    if (str.Length <= maxLen)
    {
        return str;
    }

    string pattern = @"^(.{0," + maxLen.ToString() + @"})\s"; // <-- @"^(.{0,20})\s" 
    Regex regEx = new Regex(pattern);
    var matches = regEx.Matches(str);

    if (matches.Count > 0)
    {
        return matches[0].Value.Trim();
    }
    else
    {
        return str.Substring(0, maxLen).Trim();
    }
}

Upvotes: 1

Ced
Ced

Reputation: 1207

(.{0,20})(\s|$) this regex will capture groups up to 20 characters, ending in whitespace (or end of string)

Upvotes: 2

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