Re: String performance

From:

"Bo Persson" <bop@gmb.dk>

Newsgroups:

comp.lang.c++

Date:

Sat, 20 Oct 2007 23:49:46 +0200

Message-ID:

<5nvbf0Fk8h4qU1@mid.individual.net>

Marcin Kalicinski wrote:
:: I have recently done a simple measurement of std::string
:: performance in C++, and I'm shocked how bad it is. C++ is first
:: and foremost meant to be a performance language, with near-zero
:: overhead. This holds quite well with regards to the language, but
:: overheads of the std library are absolutely abysmal. And string is
:: one of the most often used datatypes.
::
:: Test programs for reference:
::
:: // #1: C++
:: std::vector<std::string> v;
:: int main()
:: {

What happens if you add

v.reserve(10000000);

here?

:: clock_t t1 = clock();
:: for (int i = 0; i < 10000000; ++i)
:: v.push_back("poo");
:: clock_t t2 = clock();
:: cout << double(t2 - t1) / CLOCKS_PER_SEC;
:: }
::
::
:: // #2: C#
:: class Test
:: {
:: public static void Main()
:: {
:: DateTime t1 = System.DateTime.Now;
:: List<string> v = new List<string>();
:: for (int i = 0; i < 10000000; ++i)
:: v.Add("foo");
:: DateTime t2 = System.DateTime.Now;
:: Console.WriteLine(t2 - t1);
:: }
:: }
::

Are you sure you are testing std::string and not std::vector?

Bo Persson