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 whether x==1 and y==1 z==1 (it may be '1' or some other value). instead of this, is there any short way I can achieve same such as below

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

Is this possible in C#?

Solution 1

KennyTM is correct, there is no other simpler or more efficient way.

However, if you have many variables, you could also build an array of the values and use the IEnumerable.All method to verify they're all 1. More readable, IMO.

if (new[] { v1, v2, v3, v4, v5, v6, v7, v8, v9, v10 }.All(x => x == 1))

Instead of

if(v1 == 1 && v2 == 1 && v3 == 1 && v4 == 1 && v5 == 1 && v6 == 1 && v7 == 1 && v8 == 1 && v9== 1 && v10 == 1)

Solution 2

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)) { ... }

Solution 3

If you just want to testif x == y == z you can use:

var allEqual = new[] {x, y, z}.Distinct().Count() == 1;

If you want to test if they're all equal to 1, add 1 to the set:

var allEqual1 = new[] {x, y, z, 1}.Distinct().Count() == 1;

or use All as in fencliff's answer.

Solution 4

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

There are no other simple or more efficient ways.

Solution 5

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.

View more solutions

Comments

[JPReddy]

Sorry to say that I'm not expecting this answer as even I know I can achieve it with such 3 expression check. My question might not be clear enough. I wanted to achieve this in single expression as I stated above without And operator. Anyway thanks for clarifying that there is no simpler way.

[this. __curious_geek]

+1. brilliant. I'd accept this answer. It's not how much you know, it's all about how well you know whatever you already know. My answer looks silly in front of this.

[Michael Anderson]

Thing to watch out for in large sets this is O(N log N) while the accepted solution is O(N).

[DeadlyChambers]

So for an OR (||) statement you could just do .Any instead of .All?

[Żubrówka]

Just adding on top of @MichaelAnderson, performance speaking, how will that Distinct() perform if you have an enough large set with different values?

[Jazimov]

If you choose to use this in an if statement, surround the ^ (XOR) operators with parentheses as: if((x ^ y ^ z ^ 1)==0)

[theonlygusti]

@Jazimov why?.....

[Piotr Golacki]

@theonlygusti otherwise you get a compiler error

[Piotr Golacki]

this does not really work as x andy will be evaluated to a value (perhaps to 0 if they're equal) and then this value will be XOR'ed with z