我写这个怪物是为了好玩，它让你可以往返:

public static class FileUtility
{
    private const char PrefixChar = '%';
    private static readonly int MaxLength;
    private static readonly Dictionary<char,char[]> Illegals;
    static FileUtility()
    {
        List<char> illegal = new List<char> { PrefixChar };
        illegal.AddRange(Path.GetInvalidFileNameChars());
        MaxLength = illegal.Select(x => ((int)x).ToString().Length).Max();
        Illegals = illegal.ToDictionary(x => x, x => ((int)x).ToString("D" + MaxLength).ToCharArray());
    }

    public static string FilenameEncode(string s)
    {
        var builder = new StringBuilder();
        char[] replacement;
        using (var reader = new StringReader(s))
        {
            while (true)
            {
                int read = reader.Read();
                if (read == -1)
                    break;
                char c = (char)read;
                if(Illegals.TryGetValue(c,out replacement))
                {
                    builder.Append(PrefixChar);
                    builder.Append(replacement);
                }
                else
                {
                    builder.Append(c);
                }
            }
        }
        return builder.ToString();
    }

    public static string FilenameDecode(string s)
    {
        var builder = new StringBuilder();
        char[] buffer = new char[MaxLength];
        using (var reader = new StringReader(s))
        {
            while (true)
            {
                int read = reader.Read();
                if (read == -1)
                    break;
                char c = (char)read;
                if (c == PrefixChar)
                {
                    reader.Read(buffer, 0, MaxLength);
                    var encoded =(char) ParseCharArray(buffer);
                    builder.Append(encoded);
                }
                else
                {
                    builder.Append(c);
                }
            }
        }
        return builder.ToString();
    }

    public static int ParseCharArray(char[] buffer)
    {
        int result = 0;
        foreach (char t in buffer)
        {
            int digit = t - '0';
            if ((digit < 0) || (digit > 9))
            {
                throw new ArgumentException("Input string was not in the correct format");
            }
            result *= 10;
            result += digit;
        }
        return result;
    }
}

抛出异常。

if ( fileName.IndexOfAny(Path.GetInvalidFileNameChars()) > -1 )
            {
                throw new ArgumentException();
            }

或者你可以这样做

[YOUR STRING].Replace('\\', ' ').Replace('/', ' ').Replace('"', ' ').Replace('*', ' ').Replace(':', ' ').Replace('?', ' ').Replace('<', ' ').Replace('>', ' ').Replace('|', ' ').Trim();

我创建了一个扩展方法，它结合了几个建议:

在哈希集中保存非法字符 过滤ascii 127以下的字符。因为路径。getinvalidfilenamecars不包括ascii码从0到255的所有无效字符。看这里和MSDN 定义替换字符的可能性

来源:

public static class FileNameCorrector
{
    private static HashSet<char> invalid = new HashSet<char>(Path.GetInvalidFileNameChars());

    public static string ToValidFileName(this string name, char replacement = '\0')
    {
        var builder = new StringBuilder();
        foreach (var cur in name)
        {
            if (cur > 31 && cur < 128 && !invalid.Contains(cur))
            {
                builder.Append(cur);
            }
            else if (replacement != '\0')
            {
                builder.Append(replacement);
            }
        }

        return builder.ToString();
    }
}

public static class StringExtensions
      {
        public static string RemoveUnnecessary(this string source)
        {
            string result = string.Empty;
            string regex = new string(Path.GetInvalidFileNameChars()) + new string(Path.GetInvalidPathChars());
            Regex reg = new Regex(string.Format("[{0}]", Regex.Escape(regex)));
            result = reg.Replace(source, "");
            return result;
        }
    }

你可以清楚地使用方法。

这看起来是O(n)，并且不会在字符串上花费太多内存:

    private static readonly HashSet<char> invalidFileNameChars = new HashSet<char>(Path.GetInvalidFileNameChars());

    public static string RemoveInvalidFileNameChars(string name)
    {
        if (!name.Any(c => invalidFileNameChars.Contains(c))) {
            return name;
        }

        return new string(name.Where(c => !invalidFileNameChars.Contains(c)).ToArray());
    }