现在可能

Question

我不想使用{0} {1}等，而是使用{title}代替。然后以某种方式填充该数据（下面我使用了Dictionary）。此代码无效并引发异常。我想知道我是否能做类似于我想要的事情。使用{0 .. N}不是问题。我只是很好奇。

Dictionary<string, string> d = new Dictionary<string, string>();
d["a"] = "he";
d["ba"] = "llo";
d["lol"] = "world";
string a = string.Format("{a}{ba}{lol}", d);

Answer 1

不，但这种扩展方法会这样做

static string FormatFromDictionary(this string formatString, Dictionary<string, string> ValueDict) 
{
    int i = 0;
    StringBuilder newFormatString = new StringBuilder(formatString);
    Dictionary<string, int> keyToInt = new Dictionary<string,int>();
    foreach (var tuple in ValueDict)
    {
        newFormatString = newFormatString.Replace("{" + tuple.Key + "}", "{" + i.ToString() + "}");
        keyToInt.Add(tuple.Key, i);
        i++;                    
    }
    return String.Format(newFormatString.ToString(), ValueDict.OrderBy(x => keyToInt[x.Key]).Select(x => x.Value).ToArray());
}

Answer 2

检查一下，它支持格式化：

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

        return words.Aggregate(
            format,
            (current, key) =>
                {
                    int colonIndex = key.IndexOf(':');
                    return current.Replace(
                        "{" + key + "}",
                        colonIndex > 0
                            ? string.Format("{0:" + key.Substring(colonIndex + 1) + "}", values[key.Substring(0, colonIndex)])
                            : values[key].ToString());
                });
    }

使用方法：

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

Answer 3

现在可能

使用C＃6.0 Interpolated Strings，您可以执行此操作：

string name = "John";
string message = $"Hi {name}!";
//"Hi John!"

Answer 4

您可以实施自己的：

public static string StringFormat(string format, IDictionary<string, string> values)
{
    foreach(var p in values)
        format = format.Replace("{" + p.Key + "}", p.Value);
    return format;
}

Answer 5

Phil Haack在他的博客上讨论了几种方法：http://haacked.com/archive/2009/01/14/named-formats-redux.aspx。我在两个没有投诉的项目中使用了“Hanselformat”版本。

Answer 6

static public class StringFormat
{
    static private char[] separator = new char[] { ':' };
    static private Regex findParameters = new Regex(
        "\\{(?<param>.*?)\\}",
        RegexOptions.Compiled | RegexOptions.Singleline);

    static string FormatNamed(
        this string format,
        Dictionary<string, object> args)
    {
        return findParameters.Replace(
            format,
            delegate(Match match)
            {
                string[] param = match.Groups["param"].Value.Split(separator, 2);

                object value;
                if (!args.TryGetValue(param[0], out value))
                    value = match.Value;

                if ((param.Length == 2) && (param[1].Length != 0))
                    return string.Format(
                        CultureInfo.CurrentCulture,
                        "{0:" + param[1] + "}",
                        value);
                else
                    return value.ToString();
            });
    }
}

比其他扩展方法更复杂，但是这也应该允许使用非字符串值和格式化模式，所以在原始示例中：

Dictionary<string, object> d = new Dictionary<string, object>();
d["a"] = DateTime.Now;
string a = string.FormatNamed("{a:yyyyMMdd-HHmmss}", d);

也会有用......

Answer 7

自C＃6发布以来，您可以使用String Interpolation feature

解决您问题的代码：

string a = $"{d["a"]}{d["ba"]}{d["lol"]}";

Answer 8

为什么要词典？这是不必要的，而且过于复杂。一个简单的二维名称/值对数组也可以工作：

public static string Format(this string formatString, string[,] nameValuePairs)
{
    if (nameValuePairs.GetLength(1) != 2)
    {
        throw new ArgumentException("Name value pairs array must be [N,2]", nameof(nameValuePairs));
    }
    StringBuilder newFormat = new StringBuilder(formatString);
    int count = nameValuePairs.GetLength(0);
    object[] values = new object[count];
    for (var index = 0; index < count; index++)
    {
        newFormat = newFormat.Replace(string.Concat("{", nameValuePairs[index,0], "}"), string.Concat("{", index.ToString(), "}"));
        values[index] = nameValuePairs[index,1];
    }
    return string.Format(newFormat.ToString(), values);
}

致电：

string format = "{foo} = {bar} (really, it's {bar})";
string formatted = format.Format(new[,] { { "foo", "Dictionary" }, { "bar", "unnecessary" } });

结果："Dictionary = unnecessary (really, it's unnecessary)"

Answer 9

public static string StringFormat(this string format, IDictionary<string, object> values)
{
    return Regex.Matches(format, @"\{(?!\{)(.+?)\}")
            .Select(m => m.Groups[1].Value)
            .Aggregate(format, (current, key) =>
            {
                string[] splits = key.Split(":");
                string replacement = splits.Length > 1
                    ? string.Format($"{{0:{splits[1]}}}", values[splits[0]])
                    : values[key].ToString();
                return Regex.Replace(current, "(.|^)("+ Regex.Escape($"{{{key}}}")+")(.|$)", 
                                     m => m.Groups[1].ToString() == "{" && m.Groups[3].ToString() == "}"
                                        ? m.Groups[2].ToString()
                                        : m.Groups[1] + replacement + m.Groups[3]
                                    );
            });
}

这类似于另一个答案，但它考虑使用{{text}}进行转义。

Answer 10

这是一个很好的解决方案，在格式化电子邮件时非常有用：http://www.c-sharpcorner.com/UploadFile/e4ff85/string-replacement-with-named-string-placeholders/

编辑：

public static class StringExtension  
{  
    public static string Format( this string str, params Expression<Func<string,object>>[] args)  
    {  
        var parameters = args.ToDictionary( e=>string.Format("{{{0}}}",e.Parameters[0].Name), e=>e.Compile()(e.Parameters[0].Name));  

        var sb = new StringBuilder(str);  
        foreach(var kv in parameters)  
        {  
            sb.Replace( kv.Key, kv.Value != null ? kv.Value.ToString() : "");  
        }  

        return sb.ToString();  
    }  
}

使用示例：

public string PopulateString(string emailBody)  
{  
  User person = _db.GetCurrentUser();  
  string firstName = person.FirstName;    //  Peter  
  string lastName = person.LastName;      //  Pan  
  return StringExtension.Format(emailBody.Format(  
    firstname => firstName,  
    lastname => lastName  
  ));   
}

Answer 11

（您的Dictionary + foreach + string.Replace）包装在子例程或扩展方法中？

显然未经优化，但......

名为String.Format，有可能吗？

11 个答案:

现在可能