Equality comparison between multiple variables

Question

I\'ve a situation where I need to check whether multiple variables are having same data such as

var x=1;
var y=1;
var z=1;

I want to check

Answer 1

if (x == y && y == z && z == 1)

There are no other simple or more efficient ways.

Answer 2

There is how I did this:

Debug.Assert(new List<int> { l1.Count, l2.Count, l3.Count, l4.Count }.TrueForAll(
  delegate(int value) { return value == l1.Count; }), "Tables have different size.");

Answer 3

For integral types, what about:

int x = 3, y = 3, z = 3;

if((x & y & z & 3) == 3)
  //...have same data

for testing any non-zero value. It would need more checks to make this a re-usable function. But might work for inline checks of non-zero equality, as the OP described.

Answer 4

if (x == y && y == z && z == 1)

is the best you can do, because

y == z evaluates to a boolean and you can't compare x with the result:

x == (y == z)

|    |

int  bool

I would do this:

public bool AllEqual<T>(params T[] values) {
    if(values == null || values.Length == 0)
         return true;
    return values.All(v => v.Equals(values[0]));    
}

// ...

if(AllEqual(x, y, z)) { ... }

Answer 5

public static bool AllSame<T>(List<T> values)
{
    return values.Distinct().Count() == 1;
}

public static bool AllDifferent<T>(List<T> values)
{
    return values.Distinct().Count() == values.Count;
}

Answer 6

Here's a nice little recursive solution that works with all types.

class Program
{
    static void Main(string[] args)
    {
        int x = 4, y = 4, z = 4;
        Console.WriteLine(4.IsEqualToAllIn(x, y, z).ToString());
        //prints True

        string a = "str", b = "str1", c = "str";
        Console.WriteLine("str".IsEqualToAllIn(a, b, c).ToString());
        //prints False
    }
}

public static class MyExtensions
{
    public static bool IsEqualToAllIn<T>(this T valueToCompare, params T[] list)
    {
        bool prevResult = true;
        if (list.Count() > 1)
            prevResult = list[0].IsEqualToAllIn(list.Skip(1).ToArray());
        return (valueToCompare.Equals(list[0])) && prevResult;
    }
}