9

So I was making a Rock Paper Scissor game and I've sort of made adjustments to it to include life and other things. Now I got stuck with the switch statement. My if statement works fine:

private void Result_TextChanged(object sender, EventArgs e)
{
     if (playerscore == 1 || pcscore == 1)
     {
          PlayerLife.Image = Properties.Resources.Five;
     }
}

I was wondering how I could translate this to the switch statement? 

private void Result_TextChanged(object sender, EventArgs e)
{              
    switch (playerscore || pcscore)
    {
         case 1:
             PlayerLife.Image = Properties.Resources.Five;
             break;
    }
}

Doesn't seem to work.

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6
  • You have to switch on a single variable's value, and why do you want to use switch? Commented Oct 23, 2013 at 16:31
  • No that's not possible in C#. VB.NET might allow something like that though, because its Select statement is a lot more flexible than C#'s switch. Commented Oct 23, 2013 at 16:31
  • May I ask why an if statement is not appropriate in this scenario? Commented Oct 23, 2013 at 16:34
  • case is a way of selecting a bracket of code to run based on the VALUE of a given switch condition. Usually this will be a variable. In your case, using AND / OR will always only result in one of two possible values, true or false. So case is not appropriate here. Commented Oct 23, 2013 at 16:34
  • If you are coming from JavaScript where || used to pick non-falsy value than C# equivalent of JavaScript || is approximately playerscore != 0? playerscore:pcscore, or sometimes ?? for reference types (stackoverflow.com/questions/19534876/…) Commented Oct 23, 2013 at 16:41

7 Answers 7

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11

The simple answer is No. You cant use it like that.

Switch works with single expression.

You may check MSDN for details.

You may try like this:-

  if (playerscore == pcscore)
        {
            switch (playerscore)
            {
                case 1:
                PlayerLife.Image = Properties.Resources.Five;
                break;
            }
        }

EDIT:-

As commented by Jeppe Stig Nielsen in the comments, You can switch on any expression of a suitable type. That expression may contain ||. There can be many case labels associated with each switch section in a switch block.

But personally speaking that would not be a good practice to follow. You may try to use if statement for that.

You may try like this if you want:

 switch (playerscore == 1 || pcscore == 1)
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8 Comments

Oh okay. So if I wanted to make it a switch statement I have to separate the playerscore and pcscore?
@user2911044:- I think it would be better if you can use if statement for that. As a suggestion dont violate the rules of C#.
Downvote. You can switch on any expression of a suitable type. That expression may contain ||. There can be many case labels associated with each switch section in a switch block.
@JeppeStigNielsen:- Yes I agree Sir but I dont think that would be a great practice to follow! Do correct me if I am wrong:)
+1. I think that "single variable value" is confusing, and "single value" is better (like playerscore | pcscore would be fine, but 2 variables)
|
3

In C#, a switch statement resolves a single expression and compares that value with a list of possible cases:

switch(someExpression)
{
   case x: // This runs if someExpression == x
      break;
   case y: // This runs if someExpression == y
      break;
}

Now, you could switch on the expression (playerscore == 1 || pcscore == 1) like so:

switch(playerscore == 1 || pcscore == 1) // This expression is either true or false
{
   case true: // Runs if playerscore is 1 or pcscore is 1
      break;
   case false: // runs if neither playscore or pcscore are 1
      break;
}

However, the above is rather unreadable and silly. You'd be best off with the if statement:

if(playerscore == 1 || pcscore == 1)
{
   // Runs if playerscore is 1 or pcscore is 1
}
else
{
   // runs if neither playscore or pcscore are 1
}
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3 Comments

I think he meant "if ((playerscore == 1) || (pcscore == 1))"
playerscore || pcscore doesn't resolve at all in C#: they're both numbers, and unlike other languages, not everything has a truthiness.
@TimS. - Yea, I didn't read the question very carefully at all!
3

You could write it like this but why would you want to?

  switch (playerscore == 1 || pcscore == 1)
        {
            case true:
                PlayerLife.Image = Properties.Resources.Five;
                break;
            default:
                break;
        }

As Jeppe points out in the comment below, when you use || or && you end up with a bool and an if statement should be used.

Here is a great answer by @EricLippert on what can be used as the expression in a swtich statement.

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2 Comments

While this works, why switch on an expression of type bool? It is much clearer to use if or if–else for that!
@JeppeStigNielsen I agree completely, that's why I commented why would you want to in the answer.
1

What you are trying to do doesn't make sense, if playerscore = 3 and pcscore = 2 then what would playerscore || pcscore be equal to?

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4 Comments

Yeah I just realised my mistake. Hah looks like I'll be able to use switch statement after all :)
This is more of a comment than an answer, isn't it?
@Harrison Saying there is no answer is an answer.
I speculate that @user2911044 would like both case 3 and case 2 to run in that case? But in what order? And if the values were equal, should the relevant switch section run twice? Anyway, switch does not work like that.
1

If you have a whole bunch of variables, say not just two, but 5, 10, or even an unknown number, then what you can do is put all of the values that you want to compare to 1 into a collection and then act on that collection as a whole.

//this could just be a list/array accepted as a paramter, 
//can include other variables, or whatever
var scores = new []{playerscore, pcscore};

if(scores.Any(score => score == 1))
    PlayerLife.Image = Properties.Resources.Five;

switch isn't really an appropriate tool for manipulating collections like this.

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1 Comment

I think instead of data you meant scores
0

This makes no sense: in a switch statement you always want to compare with a specific type, rather than to a boolean value as follows:

switch (playerscore || pcscore)

in your case use the 'if'-statement

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Comments

0

Suppose that playerscore and pcscore are integer who has 0 or 1 as possible values

    resp = playerscore + 10 * pcscore;
    switch (resp)
    {
        case 0:
            // both are false
            break;
        case 1:
            // playerscore true
            break;
        case 10:
            // pcscore true
            break;
        case 11:
            // both are true
            break;
        default:
            // error in input data
            break;
    }
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