Weird behaviour in XCode

Question

Just wanted to get your thought on this, I recall reading that property declarations are forbidden inside switch-case statements (i.e. case:ABC int i=0; is not allowed)

I came across something rather odd this morning,

the following compiles

switch(var1) {
  case 1:
    NSLog(@"hello");
    float x = 0;
    view.setCenter(CGPointMake(x,100));
    break;
  ...

whereas the following does NOT compile

switch(var1) {
  case 1:
    float x = 0;
    view.setCenter(CGPointMake(x,100));
    break;
  ...

So it seems if you start a case expression with a statement (not declaration), it compiles. But when you try to start right away with a variable declaration, it doesn't.

What is the rationale behind this?

EDIT: Decided to make my question clearer, what difference does NSLog make so that it compiles now?

@Spectravideo328 You are right and the answer there is much better than mine. — Sulthan, Apr 17 '13 at 13:26
Thanks all, mystery resolved :) So it's not a compiler bug but it's by definition that a label must be followed by an expression, which is odd (I still haven't seen any good reason why this should be like this) — Ege Akpinar, Apr 17 '13 at 15:00

score 4 · Accepted Answer · answered Apr 17 '13 at 13:08

The NSLog doesn't make a difference here. It's the ; that is making the difference:

switch(var1) {
    case 1:
        ;
        float x = 0;
        view.setCenter(CGPointMake(x,100));
        break;

compiles. Even

 switch(var1) {
    case 1:;
        float x = 0;
        view.setCenter(CGPointMake(x,100));
        break;

What cannot compile is float (or other type) immediately after :. In other words, a command is expected after :, not a declaration.

score 0 · Answer 2 · edited May 23 '17 at 12:28

0

It does compile if you:

switch(var1) {
  case 1:
  {
    float x = 0;
    view.setCenter(CGPointMake(x,100));
  }
    break;

As for the why check this answer.

edited May 23 '17 at 12:28

Community

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answered Apr 17 '13 at 12:19

Rui Peres

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I couldn't find in neither that SO post or the 'four switch oddities' post referred by it. My question is what difference does NSLog make – Ege Akpinar Apr 17 '13 at 12:58

Weird behaviour in XCode

2 Answers2