Cfrgtkky

Currently I have a StringBuilder with some lines

        StringBuilder foo = new StringBuilder()

            .AppendLine("- one")

            .AppendLine("- two")

            .AppendLine("- three");

and I would like to setup the "- " character for each new line. Pseudo code:

        StringBuilder foo = new StringBuilder()

            .SetNewLineInitialCharacter("- ")

            .AppendLine("one")

            .AppendLine("two")

            .AppendLine("three");

I don't think Insert or Replace are methods I am looking for. I know a loop could do the trick but there is no need for it and I'm just asking if there is a way setting up "- " for one single time.

You can do this using a wrapped StringBuilder:

public class StringBuilderWrapper

{

    private readonly string _prefix;

    private readonly StringBuilder _builder;



    public StringBuilderWrapper(StringBuilder builder, string prefix)

    {

        _prefix = prefix;

        _builder = builder;

    }



    public StringBuilderWrapper AppendLine(string line)

    {

        _builder.Append(_prefix);

        _builder.AppendLine(line);



        return this;

    }



    public override string ToString()

    {

        return _builder.ToString(); 

    }

}

Which, for convenience, you can return from an extension method:

public static class StringBuilderExtensions

{

    public static StringBuilderWrapper SetNewLineInitialCharacter(this StringBuilder builder, string prefix)

    {

        return new StringBuilderWrapper(builder, prefix);

    }

}

Then call it like this:

var output = new StringBuilder()

    .SetNewLineInitialCharacter("- ")

    .AppendLine("one")

    .AppendLine("two")

    .AppendLine("three");



var outputString = output.ToString();

Which outputs:

- one

- two

- three

Without the extension method, you'd call it like this:

var output = new StringBuilderWrapper(new StringBuilder(), "- ")

    .AppendLine("one")

    .AppendLine("two")

    .AppendLine("three");

One of many ways to do this would be to wrap the StringBuilder in a separate class.

void Main()

{

    var sb = new StringBuilder();

    var foo = new MyStringBuilder(sb, "- ")

            .AppendLine("one")

            .AppendLine("two")

            .AppendLine("three");



    var result = sb.ToString();

}



public class MyStringBuilder

{

    private StringBuilder _sb;

    private string _linePrefix;



    public MyStringBuilder(StringBuilder sb, string linePrefix)

    {

            _sb = sb;

            _linePrefix = linePrefix;

    }



    public MyStringBuilder AppendLine(string line)

    {

        _sb.Append(_linePrefix);

        _sb.AppendLine(line);

        return this;

    }



    public override string ToString()

    {   

       return _sb.ToString(); 

    }

}

A simple solution could be something like that

public class CustomStringBuilder 

{

    private StringBuilder _builder;

    private string _prefix;



    public CustomStringBuilder (StringBuilder builder, string prefix)

    {

            _builder = builder;

            _prefix = prefix;

    }



    public CustomStringBuilder CustomAppendLine(string text)

    {

        _builder .Append(_prefix);

        _builder .AppendLine(text);

        return this;

    }



    public override string ToString()

    {

        return _builder.ToString(); 

    }

}

and you could call it like that:

CustomStringBuilderfoo = new CustomStringBuilder(new StringBuilder(), "- ")

            .CustomAppendLine ("one")

            .CustomAppendLine ("two")

            .CustomAppendLine ("three");