在c#中,我可以将字符串值转换为字符串文字,我将在代码中看到它的方式吗?我想用转义序列替换制表符,换行符等。

如果这段代码:

Console.WriteLine(someString);

生产:

Hello
World!

我想要这样的代码:

Console.WriteLine(ToLiteral(someString));

生产:

\tHello\r\n\tWorld!\r\n

当前回答

使用Regex.Escape(字符串):

正则表达式。Escape转义最小字符集(,*,+,?,|,{,[, (,), ^, $,。, #和空白),用转义符替换它们 代码。

其他回答

public static class StringHelpers
{
    private static Dictionary<string, string> escapeMapping = new Dictionary<string, string>()
    {
        {"\"", @"\\\"""},
        {"\\\\", @"\\"},
        {"\a", @"\a"},
        {"\b", @"\b"},
        {"\f", @"\f"},
        {"\n", @"\n"},
        {"\r", @"\r"},
        {"\t", @"\t"},
        {"\v", @"\v"},
        {"\0", @"\0"},
    };

    private static Regex escapeRegex = new Regex(string.Join("|", escapeMapping.Keys.ToArray()));

    public static string Escape(this string s)
    {
        return escapeRegex.Replace(s, EscapeMatchEval);
    }

    private static string EscapeMatchEval(Match m)
    {
        if (escapeMapping.ContainsKey(m.Value))
        {
            return escapeMapping[m.Value];
        }
        return escapeMapping[Regex.Escape(m.Value)];
    }
}

我试图将ToVerbatim添加到Hallgrim公认的答案中:

private static string ToLiteral(string input)
{
    using (var writer = new StringWriter())
    {
        using (var provider = CodeDomProvider.CreateProvider("CSharp"))
        {
            provider.GenerateCodeFromExpression(new CodePrimitiveExpression(input), writer, new CodeGeneratorOptions { IndentString = "\t" });
            var literal = writer.ToString();
            literal = literal.Replace(string.Format("\" +{0}\t\"", Environment.NewLine), "");
            return literal;
        }
    }
}

private static string ToVerbatim(string input)
{
    string literal = ToLiteral(input);
    string verbatim = "@" + literal.Replace(@"\r\n", Environment.NewLine);
    return verbatim;
}

这是一个完全可行的实现,包括Unicode和ASCII不可打印字符的转义。它没有像Hallgrim的答案那样插入“+”符号。

static string ToLiteral(string input) {
    StringBuilder literal = new StringBuilder(input.Length + 2);
    literal.Append("\"");
    foreach (var c in input) {
        switch (c) {
            case '\"': literal.Append("\\\""); break;
            case '\\': literal.Append(@"\\"); break;
            case '\0': literal.Append(@"\0"); break;
            case '\a': literal.Append(@"\a"); break;
            case '\b': literal.Append(@"\b"); break;
            case '\f': literal.Append(@"\f"); break;
            case '\n': literal.Append(@"\n"); break;
            case '\r': literal.Append(@"\r"); break;
            case '\t': literal.Append(@"\t"); break;
            case '\v': literal.Append(@"\v"); break;
            default:
                // ASCII printable character
                if (c >= 0x20 && c <= 0x7e) {
                    literal.Append(c);
                // As UTF16 escaped character
                } else {
                    literal.Append(@"\u");
                    literal.Append(((int)c).ToString("x4"));
                }
                break;
        }
    }
    literal.Append("\"");
    return literal.ToString();
}

注意,这也转义了所有Unicode字符。如果你的环境支持它们,你可以改变这一部分,只转义控制字符:

// UTF16 control characters
} else if (Char.GetUnicodeCategory(c) == UnicodeCategory.Control) {
    literal.Append(@"\u");
    literal.Append(((int)c).ToString("x4"));
} else {
    literal.Append(c);
}

使用Regex.Escape(字符串):

正则表达式。Escape转义最小字符集(,*,+,?,|,{,[, (,), ^, $,。, #和空白),用转义符替换它们 代码。

我提交了自己的实现,它处理空值,并且由于使用数组查找表、手动十六进制转换和避免开关语句,因此性能应该更好。

using System;
using System.Text;
using System.Linq;

public static class StringLiteralEncoding {
  private static readonly char[] HEX_DIGIT_LOWER = "0123456789abcdef".ToCharArray();
  private static readonly char[] LITERALENCODE_ESCAPE_CHARS;

  static StringLiteralEncoding() {
    // Per http://msdn.microsoft.com/en-us/library/h21280bw.aspx
    var escapes = new string[] { "\aa", "\bb", "\ff", "\nn", "\rr", "\tt", "\vv", "\"\"", "\\\\", "??", "\00" };
    LITERALENCODE_ESCAPE_CHARS = new char[escapes.Max(e => e[0]) + 1];
    foreach(var escape in escapes)
      LITERALENCODE_ESCAPE_CHARS[escape[0]] = escape[1];
  }

  /// <summary>
  /// Convert the string to the equivalent C# string literal, enclosing the string in double quotes and inserting
  /// escape sequences as necessary.
  /// </summary>
  /// <param name="s">The string to be converted to a C# string literal.</param>
  /// <returns><paramref name="s"/> represented as a C# string literal.</returns>
  public static string Encode(string s) {
    if(null == s) return "null";

    var sb = new StringBuilder(s.Length + 2).Append('"');
    for(var rp = 0; rp < s.Length; rp++) {
      var c = s[rp];
      if(c < LITERALENCODE_ESCAPE_CHARS.Length && '\0' != LITERALENCODE_ESCAPE_CHARS[c])
        sb.Append('\\').Append(LITERALENCODE_ESCAPE_CHARS[c]);
      else if('~' >= c && c >= ' ')
        sb.Append(c);
      else
        sb.Append(@"\x")
          .Append(HEX_DIGIT_LOWER[c >> 12 & 0x0F])
          .Append(HEX_DIGIT_LOWER[c >>  8 & 0x0F])
          .Append(HEX_DIGIT_LOWER[c >>  4 & 0x0F])
          .Append(HEX_DIGIT_LOWER[c       & 0x0F]);
    }

    return sb.Append('"').ToString();
  }
}