I work on an array that and I have to loop over it. First, I use lambda ForEach
Array
.ForEach<int>( array, ( int counter ) => {
Console.WriteLine( counter );
} );
and then I use simple foreach.
I find that simple foreach is so faster than lambda ForEach, but when i test it with generic lists, ForEach is faster than simple foreach.
why loop on array object with foreach is faster than lambda ForEach?
Update:
I test on array
I edited Keith's code a bit - On my machine foreach performed about six times faster than Array.ForEach:
class Program
{
static void Main(string[] args)
{
Benchmark(50);
}
private static void Benchmark(int iterations)
{
int[] list = Enumerable.Range(0, 100000000).ToArray();
long sum = 0;
for (int i = 0; i < iterations; i++)
{
sum += ArrayForeach(list);
}
Console.WriteLine("ForEach " + sum / iterations);
sum = 0;
for (int i = 0; i < iterations; i++)
{
sum += Foreach(list);
}
Console.WriteLine("foreach " + sum / iterations);
}
private static long Foreach(int[] list)
{
long total = 0;
var stopWatch = Stopwatch.StartNew();
foreach (var i in list)
{
total += i;
}
stopWatch.Stop();
return stopWatch.ElapsedTicks;
}
private static long ArrayForeach(int[] list)
{
long total = 0;
var stopWatch = Stopwatch.StartNew();
Array.ForEach(list, x => total += x);
stopWatch.Stop();
return stopWatch.ElapsedTicks;
}
}
On my machine (which might run a different CLR than others) it produces (in Release):
ForEach 695910
foreach 123852
In Debug:
ForEach 941030
foreach 845443
foreach enjoys some compiler optimizations, I guess mainly in accessing the list in memory.I suggest that someone with more time take a look with Reflector...
I find the lambda faster in my testing. Copy pasting MSDNs stopwatch code and decorating it with two versions of iterating a List.... ( I also changed the order of which test goes first, and I get the same timings). The Linq based iteration with a lambda goes faster.
Lambda 00:00:00.49
foreach 00:00:00.58
and the code..
var list = Enumerable.Range(0, 100000000).ToArray();
var total = 0;
var stopWatch = new Stopwatch();
stopWatch.Start();
Array.ForEach(list, x => total += x);
stopWatch.Stop();
TimeSpan ts = stopWatch.Elapsed;
string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}",
ts.Hours, ts.Minutes, ts.Seconds,
ts.Milliseconds / 10);
Console.WriteLine("RunTime " + elapsedTime);
stopWatch = new Stopwatch();
stopWatch.Start();
foreach (var i in list)
{
total += i;
}
stopWatch.Stop();
// Get the elapsed time as a TimeSpan value.
ts = stopWatch.Elapsed;
// Format and display the TimeSpan value.
elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}",
ts.Hours, ts.Minutes, ts.Seconds,
ts.Milliseconds / 10);
Console.WriteLine("RunTime " + elapsedTime);
