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eezzekl
Asked: 2020-02-24 15:40:21 +0800 CST 2020-02-24 15:40:21 +0800 CST

String.format vs StringBuilder vs String.Concat vs string + string

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I am doing a login .Net which before and after each process will fill a stringwith the message:

"proceso x realizado \n"
"proceso y saltado \n" //porque o se realiza x o y 
"proceso a fallo al sumar \n"
"proceso n [...] \n"

Each message is added to stringafter each process with all the messages it has.

As it appears in the title there are several ways to create one stringof this type.

To which my question is, which of the ways to create a stringis the one that consumes less resources or is more efficient.

It should be noted that the stringending will have at least 25 lines

c#

2 Answers

  1. Best Answer

    For the C# case :

    String.Formatinternally it uses StringBuilder:

    public static string Format(IFormatProvider provider, string format, params object[] args)
{
    if ((format == null) || (args == null))
    {
        throw new ArgumentNullException((format == null) ? "format" : "args");
    }

    StringBuilder builder = new StringBuilder(format.Length + (args.Length * 8));
    builder.AppendFormat(provider, format, args);
    return builder.ToString();
}

    operator +becomesString.Concat

    When we have this code example:

    string x = "hello";
string y = "there";
string z = "chaps";
string all = x + y + z;

    When compiled it becomes:

    string x = "hello";
string y = "there";
string z = "chaps";
string all = string.Concat(x, y, z);

    The official documentation says:

    An object concatenation operation Stringalways creates a new object from the existing string and new data. An object StringBuildermaintains a buffer to accommodate the concatenation of new data. New data is added to the buffer if space is available; Otherwise, a new, larger buffer is allocated, the data from the original buffer is copied to the new buffer, and the new data is added to the new buffer.

    Therefore:

    The execution of a concatenation operation for an object Stringor StringBuilderdepends on the frequency of memory allocations.

    (Now this answer from samjudson makes sense , where he mentions that the first execution and the order matter and will always take longer)

    In summary

    It depends on the objective of your test, since at the end of the day the format you give to your Stringalso consumes resources, since adding a simple string is not the same as adding a string that has a specific format (in this case it would be StringBuilder.Append()against StringBuilder.AppendFormat()) . Some people base the technique to use according to the number of elements they use at the moment . Like a StringBuilderhas much more functionality than just concatenation.

    Which one should you choose? The answer is it depends. For your exposed case I suggest using String.Concat, for more detailed cases the best would be StringBuilder.

    References:

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  2. The most efficient way to create a character string from the concatenation of other strings is using the class StringBuilder, whose objective, as its name indicates, is the construction of objects String.

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