C＃中的命名字符串格式

Question

有什么方法可以通過名稱而不是C＃中的位置來格式化字符串？

在python中，我可以執行類似以下示例的操作（從這里偷偷地偷了 ）：

>>> print '%(language)s has %(#)03d quote types.' % \
      {'language': "Python", "#": 2}
Python has 002 quote types.

在C＃中有什么方法可以做到這一點？ 例如說：

String.Format("{some_variable}: {some_other_variable}", ...);

能夠使用變量名來做到這一點會很好，但是字典也是可以接受的。

Answer 1

沒有內置方法可以處理此問題。

這是一種方法

string myString = "{foo} is {bar} and {yadi} is {yada}".Inject(o);

這是另一個

Status.Text = "{UserName} last logged in at {LastLoginDate}".FormatWith(user);

部分基於以上兩個方面的第三種改進方法 ，來自Phil Haack

Answer 2

我有一個剛剛發布到我的博客的實現： http : //haacked.com/archive/2009/01/04/fun-with-named-formats-string-parsing-and-edge-cases.aspx

它通過大括號轉義解決了其他實現所遇到的一些問題。 該帖子有詳細信息。 它也執行DataBinder.Eval的事情，但是仍然非常快。

Answer 3

內插字符串已添加到C＃6.0和Visual Basic 14中

兩者都是通過Visual Studio 2015中的新Roslyn編譯器引入的。

• C＃6.0：

  return "\\{someVariable} and also \\{someOtherVariable}"或
  return $"{someVariable} and also {someOtherVariable}"

  • 來源： C＃6.0中的新增功能

• VB 14：

  return $"{someVariable} and also {someOtherVariable}"

  • 來源： VB 14中的新增功能

值得注意的功能（在Visual Studio 2015 IDE中）：

• 支持語法着色 -字符串中包含的變量突出顯示
• 支持重構 -重命名時，字符串中包含的變量也將重命名
• 實際上不僅支持變量名，還支持表達式 -例如，不僅{index}有效， {(index + 1).ToString().Trim()}

請享用！ （並在VS中單擊“發送微笑”）

Answer 4

您還可以使用如下匿名類型：

    public string Format(string input, object p)
    {
        foreach (PropertyDescriptor prop in TypeDescriptor.GetProperties(p))
            input = input.Replace("{" + prop.Name + "}", (prop.GetValue(p) ?? "(null)").ToString());

        return input;
    }

當然，如果您還想解析格式，則需要更多代碼，但是可以使用以下函數來格式化字符串：

Format("test {first} and {another}", new { first = "something", another = "something else" })

Answer 5

似乎沒有開箱即用的方法。 但是，實現自己的IFormatProvider看起來很可行，該IFormatProvider鏈接到IDictionary以獲取值。

var Stuff = new Dictionary<string, object> {
   { "language", "Python" },
   { "#", 2 }
};
var Formatter = new DictionaryFormatProvider();

// Interpret {0:x} where {0}=IDictionary and "x" is hash key
Console.WriteLine string.Format(Formatter, "{0:language} has {0:#} quote types", Stuff);

輸出：

Python has 2 quote types

需要注意的是，您不能混合使用FormatProviders ，因此不能同時使用精美的文本格式。

Answer 6

框架本身沒有提供執行此操作的方法，但是您可以閱讀Scott Hanselman的這篇文章 。 用法示例：

Person p = new Person();  
string foo = p.ToString("{Money:C} {LastName}, {ScottName} {BirthDate}");  
Assert.AreEqual("$3.43 Hanselman, {ScottName} 1/22/1974 12:00:00 AM", foo); 

James Newton-King的這段代碼與之類似，可用於子屬性和索引，

string foo = "Top result for {Name} was {Results[0].Name}".FormatWith(student));

James的代碼依賴於System.Web.UI.DataBinder來解析字符串，並且需要引用System.Web，有些人不喜歡在非Web應用程序中這樣做。

編輯：哦，如果您沒有准備好屬性的對象，它們可以很好地與匿名類型配合使用：

string name = ...;
DateTime date = ...;
string foo = "{Name} - {Birthday}".FormatWith(new { Name = name, Birthday = date });

Answer 7

參見https://stackoverflow.com/questions/271398?page=2#358259

使用鏈接到擴展名，您可以編寫以下代碼：

var str = "{foo} {bar} {baz}".Format(foo=>"foo", bar=>2, baz=>new object());

然后您將獲得"foo 2 System.Object ”。

Answer 8

我認為最接近的是索引格式：

String.Format("{0} has {1} quote types.", "C#", "1");

還有一個String.Replace（），如果您願意分多個步驟進行操作，並堅信您不會在字符串的其他任何地方找到“變量”：

string MyString = "{language} has {n} quote types.";
MyString = MyString.Replace("{language}", "C#").Replace("{n}", "1");

將其擴展為使用列表：

List<KeyValuePair<string, string>> replacements = GetFormatDictionary();  
foreach (KeyValuePair<string, string> item in replacements)
{
    MyString = MyString.Replace(item.Key, item.Value);
}

您也可以通過循環訪問它的.Keys集合來使用Dictionary <string，string>來做到這一點，但是通過使用List <KeyValuePair <string，string >>，我們可以利用List的.ForEach（）方法並將其壓縮回單線：

replacements.ForEach(delegate(KeyValuePair<string,string>) item) { MyString = MyString.Replace(item.Key, item.Value);});

Lambda甚至會更簡單，但是我仍然使用.Net 2.0。 還要注意，由於.Net中的字符串是不可變的，因此當迭代使用.Replace（）時性能並不佳。 同樣，這要求以可被委托訪問的方式定義MyString變量，因此它還不是完美的。

Answer 9

我的開源庫Regextra支持命名格式（除其他外）。 它當前面向.NET 4.0+，並且在NuGet上可用。 我也有一個介紹性的博客文章： Regextra：幫助您減少（問題）{2} 。

命名格式位支持：

• 基本格式
• 嵌套屬性格式
• 字典格式
• 轉義分隔符
• 標准/自定義/ IFormatProvider字符串格式

例：

var order = new
{
    Description = "Widget",
    OrderDate = DateTime.Now,
    Details = new
    {
        UnitPrice = 1500
    }
};

string template = "We just shipped your order of '{Description}', placed on {OrderDate:d}. Your {{credit}} card will be billed {Details.UnitPrice:C}.";

string result = Template.Format(template, order);
// or use the extension: template.FormatTemplate(order);

結果：

我們剛剛運送了您於2014年2月28日發布的“小部件”訂單。 您的{credit}卡的費用為$ 1,500.00。

查看該項目的GitHub鏈接（上方）和Wiki，以獲得其他示例。

Answer 10

檢查一下：

public static string StringFormat(string format, object source)
{
    var matches = Regex.Matches(format, @"\{(.+?)\}");
    List<string> keys = (from Match matche in matches select matche.Groups[1].Value).ToList();

    return keys.Aggregate(
        format,
        (current, key) =>
        {
            int colonIndex = key.IndexOf(':');
            return current.Replace(
                "{" + key + "}",
                colonIndex > 0
                    ? DataBinder.Eval(source, key.Substring(0, colonIndex), "{0:" + key.Substring(colonIndex + 1) + "}")
                    : DataBinder.Eval(source, key).ToString());
        });
}

樣品：

string format = "{foo} is a {bar} is a {baz} is a {qux:#.#} is a really big {fizzle}";
var o = new { foo = 123, bar = true, baz = "this is a test", qux = 123.45, fizzle = DateTime.Now };
Console.WriteLine(StringFormat(format, o));

與其他解決方案相比，性能還不錯。

Answer 11

我懷疑這是否可能。 首先想到的是如何訪問本地變量名稱？

但是，可能有一些使用LINQ和Lambda表達式的巧妙方法。

Answer 12

這是我前一段時間做的。 它使用帶有單個參數的Format方法擴展String。 令人高興的是，如果您提供一個簡單的參數（例如int），它將使用標准的string.Format格式，但是如果您使用類似匿名類型的名稱，它也會起作用。

用法示例：

"The {Name} family has {Children} children".Format(new { Children = 4, Name = "Smith" })

將導致“史密斯一家有4個孩子”。

它不會瘋狂​​綁定諸如數組和索引器之類的東西。 但這是超級簡單和高性能。

    public static class AdvancedFormatString
{

    /// <summary>
    /// An advanced version of string.Format.  If you pass a primitive object (string, int, etc), it acts like the regular string.Format.  If you pass an anonmymous type, you can name the paramters by property name.
    /// </summary>
    /// <param name="formatString"></param>
    /// <param name="arg"></param>
    /// <returns></returns>
    /// <example>
    /// "The {Name} family has {Children} children".Format(new { Children = 4, Name = "Smith" })
    /// 
    /// results in 
    /// "This Smith family has 4 children
    /// </example>
    public static string Format(this string formatString, object arg, IFormatProvider format = null)
    {
        if (arg == null)
            return formatString;

        var type = arg.GetType();
        if (Type.GetTypeCode(type) != TypeCode.Object || type.IsPrimitive)
            return string.Format(format, formatString, arg);

        var properties = TypeDescriptor.GetProperties(arg);
        return formatString.Format((property) =>
            {
                var value = properties[property].GetValue(arg);
                return Convert.ToString(value, format);
            });
    }


    public static string Format(this string formatString, Func<string, string> formatFragmentHandler)
    {
        if (string.IsNullOrEmpty(formatString))
            return formatString;
        Fragment[] fragments = GetParsedFragments(formatString);
        if (fragments == null || fragments.Length == 0)
            return formatString;

        return string.Join(string.Empty, fragments.Select(fragment =>
            {
                if (fragment.Type == FragmentType.Literal)
                    return fragment.Value;
                else
                    return formatFragmentHandler(fragment.Value);
            }).ToArray());
    }


    private static Fragment[] GetParsedFragments(string formatString)
    {
        Fragment[] fragments;
        if ( parsedStrings.TryGetValue(formatString, out fragments) )
        {
            return fragments;
        }
        lock (parsedStringsLock)
        {
            if ( !parsedStrings.TryGetValue(formatString, out fragments) )
            {
                fragments = Parse(formatString);
                parsedStrings.Add(formatString, fragments);
            }
        }
        return fragments;
    }

    private static Object parsedStringsLock = new Object();
    private static Dictionary<string,Fragment[]> parsedStrings = new Dictionary<string,Fragment[]>(StringComparer.Ordinal);

    const char OpeningDelimiter = '{';
    const char ClosingDelimiter = '}';

    /// <summary>
    /// Parses the given format string into a list of fragments.
    /// </summary>
    /// <param name="format"></param>
    /// <returns></returns>
    static Fragment[] Parse(string format)
    {
        int lastCharIndex = format.Length - 1;
        int currFragEndIndex;
        Fragment currFrag = ParseFragment(format, 0, out currFragEndIndex);

        if (currFragEndIndex == lastCharIndex)
        {
            return new Fragment[] { currFrag };
        }

        List<Fragment> fragments = new List<Fragment>();
        while (true)
        {
            fragments.Add(currFrag);
            if (currFragEndIndex == lastCharIndex)
            {
                break;
            }
            currFrag = ParseFragment(format, currFragEndIndex + 1, out currFragEndIndex);
        }
        return fragments.ToArray();

    }

    /// <summary>
    /// Finds the next delimiter from the starting index.
    /// </summary>
    static Fragment ParseFragment(string format, int startIndex, out int fragmentEndIndex)
    {
        bool foundEscapedDelimiter = false;
        FragmentType type = FragmentType.Literal;

        int numChars = format.Length;
        for (int i = startIndex; i < numChars; i++)
        {
            char currChar = format[i];
            bool isOpenBrace = currChar == OpeningDelimiter;
            bool isCloseBrace = isOpenBrace ? false : currChar == ClosingDelimiter;

            if (!isOpenBrace && !isCloseBrace)
            {
                continue;
            }
            else if (i < (numChars - 1) && format[i + 1] == currChar)
            {//{{ or }}
                i++;
                foundEscapedDelimiter = true;
            }
            else if (isOpenBrace)
            {
                if (i == startIndex)
                {
                    type = FragmentType.FormatItem;
                }
                else
                {

                    if (type == FragmentType.FormatItem)
                        throw new FormatException("Two consequtive unescaped { format item openers were found.  Either close the first or escape any literals with another {.");

                    //curr character is the opening of a new format item.  so we close this literal out
                    string literal = format.Substring(startIndex, i - startIndex);
                    if (foundEscapedDelimiter)
                        literal = ReplaceEscapes(literal);

                    fragmentEndIndex = i - 1;
                    return new Fragment(FragmentType.Literal, literal);
                }
            }
            else
            {//close bracket
                if (i == startIndex || type == FragmentType.Literal)
                    throw new FormatException("A } closing brace existed without an opening { brace.");

                string formatItem = format.Substring(startIndex + 1, i - startIndex - 1);
                if (foundEscapedDelimiter)
                    formatItem = ReplaceEscapes(formatItem);//a format item with a { or } in its name is crazy but it could be done
                fragmentEndIndex = i;
                return new Fragment(FragmentType.FormatItem, formatItem);
            }
        }

        if (type == FragmentType.FormatItem)
            throw new FormatException("A format item was opened with { but was never closed.");

        fragmentEndIndex = numChars - 1;
        string literalValue = format.Substring(startIndex);
        if (foundEscapedDelimiter)
            literalValue = ReplaceEscapes(literalValue);

        return new Fragment(FragmentType.Literal, literalValue);

    }

    /// <summary>
    /// Replaces escaped brackets, turning '{{' and '}}' into '{' and '}', respectively.
    /// </summary>
    /// <param name="value"></param>
    /// <returns></returns>
    static string ReplaceEscapes(string value)
    {
        return value.Replace("{{", "{").Replace("}}", "}");
    }

    private enum FragmentType
    {
        Literal,
        FormatItem
    }

    private class Fragment
    {

        public Fragment(FragmentType type, string value)
        {
            Type = type;
            Value = value;
        }

        public FragmentType Type
        {
            get;
            private set;
        }

        /// <summary>
        /// The literal value, or the name of the fragment, depending on fragment type.
        /// </summary>
        public string Value
        {
            get;
            private set;
        }


    }

}

Answer 13

private static Regex s_NamedFormatRegex = new Regex(@"\{(?!\{)(?<key>[\w]+)(:(?<fmt>(\{\{|\}\}|[^\{\}])*)?)?\}", RegexOptions.Compiled);

public static StringBuilder AppendNamedFormat(this StringBuilder builder,IFormatProvider provider, string format, IDictionary<string, object> args)
{
    if (builder == null) throw new ArgumentNullException("builder");
    var str = s_NamedFormatRegex.Replace(format, (mt) => {
        string key = mt.Groups["key"].Value;
        string fmt = mt.Groups["fmt"].Value;
        object value = null;
        if (args.TryGetValue(key,out value)) {
            return string.Format(provider, "{0:" + fmt + "}", value);
        } else {
            return mt.Value;
        }
    });
    builder.Append(str);
    return builder;
}

public static StringBuilder AppendNamedFormat(this StringBuilder builder, string format, IDictionary<string, object> args)
{
    if (builder == null) throw new ArgumentNullException("builder");
    return builder.AppendNamedFormat(null, format, args);
}

例：

var builder = new StringBuilder();
builder.AppendNamedFormat(
@"你好,{Name},今天是{Date:yyyy/MM/dd}, 這是你第{LoginTimes}次登錄，積分{Score:{{ 0.00 }}}",
new Dictionary<string, object>() { 
    { "Name", "wayjet" },
    { "LoginTimes",18 },
    { "Score", 100.4 },
    { "Date",DateTime.Now }
});

輸出：你好，wayjet，今天是2011-05-04，這是你第18次登錄，積分{100.40}

Answer 14

這是任何對象的簡單方法：

    using System.Text.RegularExpressions;
    using System.ComponentModel;

    public static string StringWithFormat(string format, object args)
    {
        Regex r = new Regex(@"\{([A-Za-z0-9_]+)\}");

        MatchCollection m = r.Matches(format);

        var properties = TypeDescriptor.GetProperties(args);

        foreach (Match item in m)
        {
            try
            {
                string propertyName = item.Groups[1].Value;
                format = format.Replace(item.Value, properties[propertyName].GetValue(args).ToString());
            }
            catch
            {
                throw new FormatException("The format string is not valid");
            }
        }

        return format;
    }

以及如何使用它：

 DateTime date = DateTime.Now;
 string dateString = StringWithFormat("{Month}/{Day}/{Year}", date);

輸出：2/27/2012

Answer 15

我實現了一個簡單的類，它復制了String.Format的功能（使用類時除外）。 您可以使用字典或類型來定義字段。

https://github.com/SergueiFedorov/NamedFormatString

C＃6.0將此功能直接添加到了語言規范中，因此NamedFormatString是為了向后兼容。

Answer 16

我以與現有解決方案稍有不同的方式解決了這個問題。 它執行命名項替換的核心（而不是某些項完成的反射位）。 這是非常快速和簡單的...這是我的解決方案：

/// <summary>
/// Formats a string with named format items given a template dictionary of the items values to use.
/// </summary>
public class StringTemplateFormatter
{
    private readonly IFormatProvider _formatProvider;

    /// <summary>
    /// Constructs the formatter with the specified <see cref="IFormatProvider"/>.
    /// This is defaulted to <see cref="CultureInfo.CurrentCulture">CultureInfo.CurrentCulture</see> if none is provided.
    /// </summary>
    /// <param name="formatProvider"></param>
    public StringTemplateFormatter(IFormatProvider formatProvider = null)
    {
        _formatProvider = formatProvider ?? CultureInfo.CurrentCulture;
    }

    /// <summary>
    /// Formats a string with named format items given a template dictionary of the items values to use.
    /// </summary>
    /// <param name="text">The text template</param>
    /// <param name="templateValues">The named values to use as replacements in the formatted string.</param>
    /// <returns>The resultant text string with the template values replaced.</returns>
    public string FormatTemplate(string text, Dictionary<string, object> templateValues)
    {
        var formattableString = text;
        var values = new List<object>();
        foreach (KeyValuePair<string, object> value in templateValues)
        {
            var index = values.Count;
            formattableString = ReplaceFormattableItem(formattableString, value.Key, index);
            values.Add(value.Value);
        }
        return String.Format(_formatProvider, formattableString, values.ToArray());
    }

    /// <summary>
    /// Convert named string template item to numbered string template item that can be accepted by <see cref="string.Format(string,object[])">String.Format</see>
    /// </summary>
    /// <param name="formattableString">The string containing the named format item</param>
    /// <param name="itemName">The name of the format item</param>
    /// <param name="index">The index to use for the item value</param>
    /// <returns>The formattable string with the named item substituted with the numbered format item.</returns>
    private static string ReplaceFormattableItem(string formattableString, string itemName, int index)
    {
        return formattableString
            .Replace("{" + itemName + "}", "{" + index + "}")
            .Replace("{" + itemName + ",", "{" + index + ",")
            .Replace("{" + itemName + ":", "{" + index + ":");
    }
}

它以以下方式使用：

    [Test]
    public void FormatTemplate_GivenANamedGuid_FormattedWithB_ShouldFormatCorrectly()
    {
        // Arrange
        var template = "My guid {MyGuid:B} is awesome!";
        var templateValues = new Dictionary<string, object> { { "MyGuid", new Guid("{A4D2A7F1-421C-4A1D-9CB2-9C2E70B05E19}") } };
        var sut = new StringTemplateFormatter();
        // Act
        var result = sut.FormatTemplate(template, templateValues);
        //Assert
        Assert.That(result, Is.EqualTo("My guid {a4d2a7f1-421c-4a1d-9cb2-9c2e70b05e19} is awesome!"));
    }

希望有人覺得這有用！

Answer 17

即使已接受的答案提供了一些很好的示例，.Inject以及一些Haack示例也無法處理轉義。 許多服務器還嚴重依賴於Regex（速度較慢）或DataBinder.Eval（在.NET Core和某些其他環境中不可用）。

考慮到這一點，我編寫了一個基於狀態機的簡單解析器，該解析器通過字符流式傳輸，並逐字符地寫入StringBuilder輸出。 它被實現為String擴展方法，並且可以接受Dictionary<string, object>或帶有參數的object作為輸入（使用反射）。

當輸入包含不平衡的花括號和/或其他錯誤時，它將處理{{{escaping}}}無限級別並引發FormatException 。

public static class StringExtension {
    /// <summary>
    /// Extension method that replaces keys in a string with the values of matching object properties.
    /// </summary>
    /// <param name="formatString">The format string, containing keys like {foo} and {foo:SomeFormat}.</param>
    /// <param name="injectionObject">The object whose properties should be injected in the string</param>
    /// <returns>A version of the formatString string with keys replaced by (formatted) key values.</returns>
    public static string FormatWith(this string formatString, object injectionObject) {
        return formatString.FormatWith(GetPropertiesDictionary(injectionObject));
    }

    /// <summary>
    /// Extension method that replaces keys in a string with the values of matching dictionary entries.
    /// </summary>
    /// <param name="formatString">The format string, containing keys like {foo} and {foo:SomeFormat}.</param>
    /// <param name="dictionary">An <see cref="IDictionary"/> with keys and values to inject into the string</param>
    /// <returns>A version of the formatString string with dictionary keys replaced by (formatted) key values.</returns>
    public static string FormatWith(this string formatString, IDictionary<string, object> dictionary) {
        char openBraceChar = '{';
        char closeBraceChar = '}';

        return FormatWith(formatString, dictionary, openBraceChar, closeBraceChar);
    }
        /// <summary>
        /// Extension method that replaces keys in a string with the values of matching dictionary entries.
        /// </summary>
        /// <param name="formatString">The format string, containing keys like {foo} and {foo:SomeFormat}.</param>
        /// <param name="dictionary">An <see cref="IDictionary"/> with keys and values to inject into the string</param>
        /// <returns>A version of the formatString string with dictionary keys replaced by (formatted) key values.</returns>
    public static string FormatWith(this string formatString, IDictionary<string, object> dictionary, char openBraceChar, char closeBraceChar) {
        string result = formatString;
        if (dictionary == null || formatString == null)
            return result;

        // start the state machine!

        // ballpark output string as two times the length of the input string for performance (avoids reallocating the buffer as often).
        StringBuilder outputString = new StringBuilder(formatString.Length * 2);
        StringBuilder currentKey = new StringBuilder();

        bool insideBraces = false;

        int index = 0;
        while (index < formatString.Length) {
            if (!insideBraces) {
                // currently not inside a pair of braces in the format string
                if (formatString[index] == openBraceChar) {
                    // check if the brace is escaped
                    if (index < formatString.Length - 1 && formatString[index + 1] == openBraceChar) {
                        // add a brace to the output string
                        outputString.Append(openBraceChar);
                        // skip over braces
                        index += 2;
                        continue;
                    }
                    else {
                        // not an escaped brace, set state to inside brace
                        insideBraces = true;
                        index++;
                        continue;
                    }
                }
                else if (formatString[index] == closeBraceChar) {
                    // handle case where closing brace is encountered outside braces
                    if (index < formatString.Length - 1 && formatString[index + 1] == closeBraceChar) {
                        // this is an escaped closing brace, this is okay
                        // add a closing brace to the output string
                        outputString.Append(closeBraceChar);
                        // skip over braces
                        index += 2;
                        continue;
                    }
                    else {
                        // this is an unescaped closing brace outside of braces.
                        // throw a format exception
                        throw new FormatException($"Unmatched closing brace at position {index}");
                    }
                }
                else {
                    // the character has no special meaning, add it to the output string
                    outputString.Append(formatString[index]);
                    // move onto next character
                    index++;
                    continue;
                }
            }
            else {
                // currently inside a pair of braces in the format string
                // found an opening brace
                if (formatString[index] == openBraceChar) {
                    // check if the brace is escaped
                    if (index < formatString.Length - 1 && formatString[index + 1] == openBraceChar) {
                        // there are escaped braces within the key
                        // this is illegal, throw a format exception
                        throw new FormatException($"Illegal escaped opening braces within a parameter - index: {index}");
                    }
                    else {
                        // not an escaped brace, we have an unexpected opening brace within a pair of braces
                        throw new FormatException($"Unexpected opening brace inside a parameter - index: {index}");
                    }
                }
                else if (formatString[index] == closeBraceChar) {
                    // handle case where closing brace is encountered inside braces
                    // don't attempt to check for escaped braces here - always assume the first brace closes the braces
                    // since we cannot have escaped braces within parameters.

                    // set the state to be outside of any braces
                    insideBraces = false;

                    // jump over brace
                    index++;

                    // at this stage, a key is stored in current key that represents the text between the two braces
                    // do a lookup on this key
                    string key = currentKey.ToString();
                    // clear the stringbuilder for the key
                    currentKey.Clear();

                    object outObject;

                    if (!dictionary.TryGetValue(key, out outObject)) {
                        // the key was not found as a possible replacement, throw exception
                        throw new FormatException($"The parameter \"{key}\" was not present in the lookup dictionary");
                    }

                    // we now have the replacement value, add the value to the output string
                    outputString.Append(outObject);

                    // jump to next state
                    continue;
                } // if }
                else {
                    // character has no special meaning, add it to the current key
                    currentKey.Append(formatString[index]);
                    // move onto next character
                    index++;
                    continue;
                } // else
            } // if inside brace
        } // while

        // after the loop, if all braces were balanced, we should be outside all braces
        // if we're not, the input string was misformatted.
        if (insideBraces) {
            throw new FormatException("The format string ended before the parameter was closed.");
        }

        return outputString.ToString();
    }

    /// <summary>
    /// Creates a Dictionary from an objects properties, with the Key being the property's
    /// name and the Value being the properties value (of type object)
    /// </summary>
    /// <param name="properties">An object who's properties will be used</param>
    /// <returns>A <see cref="Dictionary"/> of property values </returns>
    private static Dictionary<string, object> GetPropertiesDictionary(object properties) {
        Dictionary<string, object> values = null;
        if (properties != null) {
            values = new Dictionary<string, object>();
            PropertyDescriptorCollection props = TypeDescriptor.GetProperties(properties);
            foreach (PropertyDescriptor prop in props) {
                values.Add(prop.Name, prop.GetValue(properties));
            }
        }
        return values;
    }
}

最終，所有邏輯都歸結為10種主要狀態-例如，當狀態機位於括號外部且同樣位於括號內部時，下一個字符要么是一個開括號，一個轉義的開放括號，一個閉合的括號，一個轉義的封閉括號，或普通字符。 這些條件中的每一個都隨着循環的進行而單獨處理，將字符添加到輸出StringBuffer或鍵StringBuffer 。 當參數關閉時，鍵StringBuffer的值用於在字典中查找參數的值，然后將其推入輸出StringBuffer 。 最后，返回輸出StringBuffer的值。

Answer 18

string language = "Python";
int numquotes = 2;
string output = language + " has "+ numquotes + " language types.";

編輯：我應該說的是，“不，我不相信C＃支持您要執行的操作。這與您將要實現的目標非常接近。”