Improve the performance of a pointer method

Question

Here’s the code working:

string string_pick(string text, string tag, char caractere)
{
    int index = text.IndexOf(tag);
    return text.Substring(index + tag.Length, text.IndexOf(caractere, index + tag.Length + 1) - (index + tag.Length));
}

Working example:

string x = "kkkkkkkkkkkk jjjjjjjjjjj oloco icaro alguma coisa algumas palavras várias loucuras name:'icaro' lalala huhuasd sdiufhidf sdifuhisuhdf kkkkkkk";
string temporaria = string_pick(x,"name:'",'\'');

The temporary will be "expensive".

Well, how are you gonna mess with a string gigantic, I would like to just access that part of memory and not copy the string again (in the case of what the function argument is doing).

In C++ I solved so:

string string_pick(string *text, string tag, char caractere)
{
    int index = (*text).find(tag);
    return (*text).substr(index + tag.length(), (*text).find(caractere, index + tag.length() + 1) - (index + tag.length()));
}

Answer 1

Before anything else do crazy things that "work" is not programming. Doing what is right is programming. Working is not a parameter to know if it is right. I will not say whether it is right or not because there is not enough information for this.

Even if it were possible to put the pointer in C# (there is even how, but in very specific situations that are not worth talking here) doing what you are trying would not solve anything to save memory since within the method is already creating a new instance. If there is any problem of memory consumption, and even this is questionable, it is within the method and not in its communication with the external world that only copies the reference and is very efficient.

If it were another problem the class StringBuilder could be a solution. But the case doesn’t even demonstrate a real performance problem or excessive allocation. And if you have the question you should demonstrate. And you should only worry about that if the problem is real and not just an assumption.

The code written in C++ is not at all more efficient than the one written in C#. Alias is a complete unnecessariness to use pointer there. He’s just creating a meaningless indirect. He’s probably crediting a quality to the pointer that he doesn’t have.

The code can be simplified and have a better nomenclature. You can start by using the name in the pattern StringPick(). The names of the parameters could indicate their function better there, not only say what will be in it, this type already says.

Just to give you an idea of what can be improved. I would do better if I knew the actual requirements.

Behold working in the ideone. And in the .NET Fiddle. Also put on the Github for future reference.