Question

I was reviewing some code, and I found something that looked like this:

public class MyClass
{
    public bool IsEditable { get; set; }

    public void HandleInput()
    {
        if (IsEditable.Equals(false))
        {
            //do stuff
        }
    }
}

As far as I know, (IsEditable.Equals(false)) is identical to (IsEditable == false) (and also the same as (!IsEditable)).

Besides personal preference, is there any difference at all between .Equals() and ==, specifically when used to compare bools?

Answer 1

The Equals way appears to be significantly slower – roughly 2.7 times in debug mode, and more than seven times in release mode.

Here is my quick and dirty benchmark:

public static void Main() {
    bool a = bool.Parse("false");
    bool b = bool.Parse("true");
    bool c = bool.Parse("true");
    var sw = new Stopwatch();
    const int Max = 1000000000;
    int count = 0;
    sw.Start();
    // The loop will increment count Max times; let's measure how long it takes
    for (int i = 0; i != Max; i++) {
        count++;
    }
    sw.Stop();
    var baseTime = sw.ElapsedMilliseconds;
    sw.Start();
    count = 0;
    for (int i = 0; i != Max; i++) {
        if (a.Equals(c)) count++;
        if (b.Equals(c)) count++;
    }
    sw.Stop();
    Console.WriteLine(sw.ElapsedMilliseconds - baseTime);
    sw.Reset();
    count = 0;
    sw.Start();
    for (int i = 0; i != Max; i++) {
        if (a==c) count++;
        if (b==c) count++;
    }
    sw.Stop();
    Console.WriteLine(sw.ElapsedMilliseconds - baseTime);
    sw.Reset();
    count = 0;
    sw.Start();
    for (int i = 0; i != Max; i++) {
        if (!a) count++;
        if (!b) count++;
    }
    sw.Stop();
    Console.WriteLine(sw.ElapsedMilliseconds - baseTime);
}

Running this produces the following results:

In debug mode

8959
2950
1874

In release mode

5348
751
7

Equals appears to be the slowest. There appears to be little difference between == and !=. However, if (!boolExpr) appears to be the clear winner.