Is there a “String.Format” that can accept named input parameters instead of index placeholders? [duplicate]

Answer 1

If you don't have C#6 available in your project you can use Linq's .Aggregate():

    var str = "Her name is @name and she's @age years old";

    var parameters = new Dictionary();
    parameters.Add("@name", "Lisa");
    parameters.Add("@age", 10);

    str = parameters.Aggregate(str, (current, parameter)=> current.Replace(parameter.Key, parameter.Value.ToString()));

If you want something matching the specific syntax in the question you can put together a pretty simple class based on Aggregate:

public class StringFormatter{

    public string Str {get;set;}

    public Dictionary Parameters {get;set;}

    public StringFormatter(string p_str){
        Str = p_str;
        Parameters = new Dictionary();
    }

    public void Add(string key, object val){
        Parameters.Add(key, val);
    }

    public override string ToString(){
        return Parameters.Aggregate(Str, (current, parameter)=> current.Replace(parameter.Key, parameter.Value.ToString()));
    }

}

Usable like:

var str = new StringFormatter("Her name is @name and she's @age years old");
str.Add("@name", "Lisa");
str.Add("@age", 10);

Console.WriteLine(str);

Note that this is clean-looking code that's geared to being easy-to-understand over performance.