CODEWITHSUNDEEP
gcc
Forester
Forester

Reputation: 135

What is an innermost "if" statement and an enclosing "if"?

First, please allow me to post a screenshot of the man page of GCC.

enter image description here

The sentence just above the second bundle of demo code confuses me, which is written as "so there is no way the 'else' could belong to the enclosing 'if'." As far as I try to get the idea of the author, the innermost if statement is if(b) and foo();. He intended to refer to if(b) when he said the "enclosing 'if'". But if my guess is right, the demo code should be like this:

    {
       if(a)
          {
             if(b)
                foo();
          }
       else
          bar();
    }

Am I right? The question turns out to be what an "enclosing 'if' " is.

Upvotes: 1

Views: 482

Answers (2)

wholerabbit
wholerabbit

Reputation: 11536

As far as I try to get the idea of the author, the innermost if statement is if(b) and foo();

Yes. And the else is a clause of it, not a clause of the enclosing if.

He intended to refer to if(b) when he said the "enclosing 'if'".

No. S/he was discussing a means of making it clear that the else belongs to the innermost if and not the enclosing one. Clear to the compiler, that is, so that it won't throw this warning.

Beyond that, the two examples are functionally identical. The only difference is that one will provoke a warning. Your version with braces is functionally different than those two -- it makes the else a clause of the enclosing if(a).

Upvotes: 1

Tim
Tim

Reputation: 1469

The "enclosing if" is the if in whose body another ("inner") if is "enclosed".

The sentence that confuses you is correct. The paragraph states, that you should put the parenthesis as shown in the second example to achieve the same result as in the first example (but without a warning from gcc).

If you want to have code as it is suggested by the indentation of example 1, your example would be correct.

Now what the sentence means is: In example 1 the else clause belongs to the inner if, but this could only be by accident (when the behaviour in your example is desired). When you write the code as it is in example 2, "there is no way" that you could have intended this.

Upvotes: 4

Related Questions