Condition question with VC++ 2008

okay i have the following code the first condition produces a warning, and the second doesnt. I am curious as to why it produces a warning in the first place.

Code:

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static const int A = 1;
static const int B = 2;

int main()
{
  if ( SomeFunc() == ( A || B ) ) // produces warning saying '==' : unsafe mix of type 'int' and type 'bool' in operation
    //do something
  if ( SomeFunc() == (int)( A || B ) ) //no warning due to cast, is there a problem with this?
    //do the same thing

}

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Thank you for any insight.

The warning is not required by the Standard, but is an attempt to be helpful. In this case I think it makes sense.

The result of (A || B) is a bool. But what does SomeFunc() return? If it returns a bool, well and good. But it seems to return an int, and perhaps you did not intend to compare an int with a bool. This is what the warning is getting at.

Yea, but how do i check if the function returned 2 integers?

Quote:

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Yea, but how do i check if the function returned 2 integers?

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The function cannot return two integers, it can only return one integer. Did you write it yourself?

I said that the wrong way.
1. Yes i do have class i made that allows a functions to return multiple values in a sense.
2. I meant to ask how do i see which of the two integers the given function returned.

What you want is probably something like this:

Code:

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int x = SomeFunc();
if (x == 2 || x == 1) ...

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--
Mats

Oh... so i can't do it by the return value inside the condition statement. Thank you.

So, SomeFunc returns an integer and you want to check if the return value is either A or B.

See, how the compiler got that warning right. This code indeed did something else than you intended. A || B produces true, which you cast to int in your attempt to suppress the warning, hence it becomes 1 and you end up checking if SomeFunc returns 1.

Quote:

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Originally Posted by Raigne

Oh... so i can't do it by the return value inside the condition statement. Thank you.

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Well, if you want to be "complicated", you could do this:

Code:

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int x;
if ((x = SomeFunc()) == 1 || x == 2) ...

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But note the extra paranthesis that you need, if you get that wrong, it will still compile nicely, but the test will assign x with the value of (SomeFunc() == 1), which is either 0 or 1 depending on the return value from SomeFunc().

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Mats