Saturday, November 21, 2009

String Compare Performance in D

A while ago I was measuring performance of string comparison in .NET. Today I played with string type in D programming language and decided to make similar tests.

D is relatively new language with some good perspectives (by the way Andrei Alexandrescu is engaged in D development).

Here is relatively simple code, that I have used to make the tests:

import std.string;
import std.stdio;

string cmp1 = "SomeString";
string cmp2 = "Someotherstring";
auto iters = 100000;

void test_f()
    for(int i = 0; i < iters; i++) { auto res = icmp(cmp1, cmp2); }

void test_equal()
    for(int i = 0; i < iters; i++) { auto res = cmp1 == cmp2; }

void main()
    ulong[] results;
    int mean1 = 0;
    int mean2 = 0;
    for(int i = 0; i < 5; i++)
        results = benchmark!(test_f, test_equal)(1, results);
 mean1 += results[0];
 mean2 += results[1];
 writefln("Test_f: %d", results[0]);
 writefln("Test_equal: %d", results[1]);
    mean1 = mean1 / 5;
    mean2 = mean2 / 5;
    writefln("Mean Test_f: %d", mean1);
    writefln("Mean Test_equal %d", mean2);
Test results where interesting:
Test_f: 21
Test_equal: 2
Test_f: 21
Test_equal: 2
Test_f: 22
Test_equal: 2
Test_f: 14
Test_equal: 1
Test_f: 12
Test_equal: 1
Mean Test_f: 18
Mean Test_equal 1
18 millis for 100000 iterations looks pretty nice. It is faster then .NET string case insensitive ordinal string comparison. If you remember: .NET version completed in about 26 milliseconds. Second test function just compares two values for equality, I assume that mere pointer compare is made.

I have decided to give this relatively new language a try, it is highly possible that there will be more posts about D in this blog :).

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