在 .NET C# 中截断整个单词的字符串

Truncate string on whole words in .NET C#

提问by TimS

I am trying to truncate some long text in C#, but I don't want my string to be cut off part way through a word. Does anyone have a function that I can use to truncate my string at the end of a word?

我试图在 C# 中截断一些长文本，但我不希望我的字符串在一个单词中被截断。有没有人有一个函数可以用来在单词末尾截断我的字符串？

E.g:

例如：

"This was a long string..."

Not:

不是：

"This was a long st..."

采纳答案by TimS

Thanks for your answer Dave. I've tweaked the function a bit and this is what I'm using ... unless there are any more comments ;)

感谢您的回答戴夫。我已经稍微调整了这个功能，这就是我正在使用的......除非有更多评论;）

public static string TruncateAtWord(this string input, int length)
{
    if (input == null || input.Length < length)
        return input;
    int iNextSpace = input.LastIndexOf(" ", length, StringComparison.Ordinal);
    return string.Format("{0}…", input.Substring(0, (iNextSpace > 0) ? iNextSpace : length).Trim());
}

回答by Dave

Try the following. It is pretty rudimentary. Just finds the first space starting at the desired length.

请尝试以下操作。这是非常初级的。只需找到从所需长度开始的第一个空格。

public static string TruncateAtWord(this string value, int length) {
    if (value == null || value.Length < length || value.IndexOf(" ", length) == -1)
        return value;

    return value.Substring(0, value.IndexOf(" ", length));
}

回答by mlsteeves

If you are using windows forms, in the Graphics.DrawString method, there is an option in StringFormat to specify if the string should be truncated, if it does not fit into the area specified. This will handle adding the ellipsis as necessary.

如果您使用 Windows 窗体，则在 Graphics.DrawString 方法中，StringFormat 中有一个选项用于指定是否应截断字符串，如果字符串不适合指定的区域。这将根据需要处理添加省略号。

http://msdn.microsoft.com/en-us/library/system.drawing.stringtrimming.aspx

http://msdn.microsoft.com/en-us/library/system.drawing.stringtrimming.aspx

回答by Douglas Ludlow

I took your approach a little further:

我更进一步地采用了你的方法：

public string TruncateAtWord(string value, int length)
{
    if (value == null || value.Trim().Length <= length)
        return value;

    int index = value.Trim().LastIndexOf(" ");

    while ((index + 3) > length)
        index = value.Substring(0, index).Trim().LastIndexOf(" ");

    if (index > 0)
        return value.Substring(0, index) + "...";

    return value.Substring(0, length - 3) + "...";
}

I'm using this to truncate tweets.

我正在使用它来截断推文。

回答by Contra

My contribution:

我的贡献：

public static string TruncateAtWord(string text, int maxCharacters, string trailingStringIfTextCut = "…")
{
    if (text == null || (text = text.Trim()).Length <= maxCharacters) 
      return text;

    int trailLength = trailingStringIfTextCut.StartsWith("&") ? 1 
                                                              : trailingStringIfTextCut.Length; 
    maxCharacters = maxCharacters - trailLength >= 0 ? maxCharacters - trailLength 
                                                     : 0;
    int pos = text.LastIndexOf(" ", maxCharacters);
    if (pos >= 0)
        return text.Substring(0, pos) + trailingStringIfTextCut;

    return string.Empty;
}

This is what I use in my projects, with optional trailing. Text will never exceed the maxCharacters + trailing text length.

这是我在我的项目中使用的，带有可选的尾随。文本永远不会超过 maxCharacters + 尾随文本长度。

回答by Leon van Wyk

simplified, added trunking character option and made it an extension.

简化，添加中继字符选项并使其成为扩展。

    public static string TruncateAtWord(this string value, int maxLength)
    {
        if (value == null || value.Trim().Length <= maxLength)
            return value;

        string ellipse = "...";
        char[] truncateChars = new char[] { ' ', ',' };
        int index = value.Trim().LastIndexOfAny(truncateChars);

        while ((index + ellipse.Length) > maxLength)
            index = value.Substring(0, index).Trim().LastIndexOfAny(truncateChars);

        if (index > 0)
            return value.Substring(0, index) + ellipse;

        return value.Substring(0, maxLength - ellipse.Length) + ellipse;
    }

回答by Zhou Hai

I use this

我用这个

public string Truncate(string content, int length)
    {
        try
        {
            return content.Substring(0,content.IndexOf(" ",length)) + "...";
        }
        catch
        {
            return content;
        }
    }

回答by Rahul Sonthalia

Heres what i came up with. This is to get the rest of the sentence also in chunks.

这是我想出的。这是为了将句子的其余部分也分块。

public static List<string> SplitTheSentenceAtWord(this string originalString, int length)
    {
        try
        {
            List<string> truncatedStrings = new List<string>();
            if (originalString == null || originalString.Trim().Length <= length)
            {
                truncatedStrings.Add(originalString);
                return truncatedStrings;
            }
            int index = originalString.Trim().LastIndexOf(" ");

            while ((index + 3) > length)
                index = originalString.Substring(0, index).Trim().LastIndexOf(" ");

            if (index > 0)
            {
                string retValue = originalString.Substring(0, index) + "...";
                truncatedStrings.Add(retValue);

                string shortWord2 = originalString;
                if (retValue.EndsWith("..."))
                {
                    shortWord2 = retValue.Replace("...", "");
                }
                shortWord2 = originalString.Substring(shortWord2.Length);

                if (shortWord2.Length > length) //truncate it further
                {
                    List<string> retValues = SplitTheSentenceAtWord(shortWord2.TrimStart(), length);
                    truncatedStrings.AddRange(retValues);
                }
                else
                {
                    truncatedStrings.Add(shortWord2.TrimStart());
                }
                return truncatedStrings;
            }
            var retVal_Last = originalString.Substring(0, length - 3);
            truncatedStrings.Add(retVal_Last + "...");
            if (originalString.Length > length)//truncate it further
            {
                string shortWord3 = originalString;
                if (originalString.EndsWith("..."))
                {
                    shortWord3 = originalString.Replace("...", "");
                }
                shortWord3 = originalString.Substring(retVal_Last.Length);
                List<string> retValues = SplitTheSentenceAtWord(shortWord3.TrimStart(), length);

                truncatedStrings.AddRange(retValues);
            }
            else
            {
                truncatedStrings.Add(retVal_Last + "...");
            }
            return truncatedStrings;
        }
        catch
        {
            return new List<string> { originalString };
        }
    }

回答by user1795248

This solution works too (takes first 10 words from myString):

此解决方案也有效（从 myString 中获取前 10 个单词）：

String.Join(" ", myString.Split(' ').Take(10))

回答by SysCafe

Taking into account more than just a blank space separator (e.g. words can be separated by periods followed by newlines, followed by tabs, etc.), and several other edge cases, here is an appropriate extension method:

考虑到不仅仅是空格分隔符（例如，单词可以用句点后跟换行符、制表符等分隔）和其他几种边缘情况，这里是一个合适的扩展方法：

    public static string GetMaxWords(this string input, int maxWords, string truncateWith = "...", string additionalSeparators = ",-_:")
    {
        int words = 1;
        bool IsSeparator(char c) => Char.IsSeparator(c) || additionalSeparators.Contains(c);

        IEnumerable<char> IterateChars()
        {
            yield return input[0];

            for (int i = 1; i < input.Length; i++)
            {
                if (IsSeparator(input[i]) && !IsSeparator(input[i - 1]))
                    if (words == maxWords)
                    {
                        foreach (char c in truncateWith)
                            yield return c;

                        break;
                    }
                    else
                        words++;

                yield return input[i];
            }
        }

        return !input.IsNullOrEmpty()
            ? new String(IterateChars().ToArray())
            : String.Empty;
    }