I was recently thinking if I really liked to use the Multiple assignment in 'C#' or if it was less readable. In 'C' this syntax was popular as it tended to lead to smaller and quicker code.

So I wondered in C# if the multiple assigment also lead to quicker code. So I quickly wrote some test cases to see which style of code was quicker to execute...

I took a rather simplistic model to profile, in order to make the tests more repeatable and easy to follow.

The .NET code followed the followed the structure:

[STAThread] static void Main(string[] args) int Count1; int Count2; int Count3; int Count4; int Count5; int Count6; int Count7; int Count8;

        Count1 =
        Count2 =
        Count3 =
        Count4 =
        Count5 =
        Count6 =
        Count7 =
        Count8 = 100;
        
		
        DateTime time = DateTime.Now;
        for (long i = 0; i < 1000000000; i++)
        {
            int  x = 100;
            Count1 = 
            Count2 = 
            Count3 = 
            Count4 = 
            Count5 = 
            Count6 = 
            Count7 = 
            Count8 = x;
        }

        TimeSpan span = DateTime.Now - time;
        Console.WriteLine("Time taken{0}", span.TotalMilliseconds / 1000.0);

}

Test .NET 1.1 Debug Mode .NET 1.1 under the debugger .NET 1.1 Release Mode Count1=x;Count2=x;..... 7 7 4.5 Count1=Count2=Count3 ...=x; 9.5 9.5 4.5

Results are in seconds

I did test out directly setting the values eg Count1=100; Count2=100; etc as well as using strings. These variations appeared to give similar results. I carried out the same expermiment under .NET 2 and the results were similar just slightly slower in debug mode.

The machine that carried out the tests was an Intel 3.4Ghz P4 running XP SP2 with 1GB RAM.

I guess as ever this proves that it is more important to write readable code that requires the minimum of maintanance, rather than trying to outwit the compiler/CLR.

So would I use the multiple assignment? Probably not as much as I used to, but when it leads to easier to read code then yes.

[http://www.simple-talk.com/community/blogs/ davidc/archive/2006/01/25/183.aspx]