GCC, Switch( condition ) & Case

Hi,

I encounter an error on using SWITCH/CASE C/C++ commands under GCC ... I don't understand why because I think I use correctly the functions :

Here is the error :
setup.c:104:error: expected expression before 'default'

Here is the code :


Strange. not ?
Or I am wrong again ?

EDIT :
Forget, I've found the error ... default does not need "case" before ... :p

@freddix

You need to put "break;" at the end of each case part, otherwise the code continues executing through the rest of the cases.

@xeron
I suspected that.
Thank you.

@freddix
I don't know about C++ but in C you will always end up with your DMode variable equal to the default case if you don't but "break" statements after each case like this:
switch( Depth ){
case 32:
DMode = GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH;
break;
case 24:
DMode = GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH;
break;
case 16:
DMode = GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH;
break;
case 8:
DMode = GLUT_DOUBLE | GL_COLOR_INDEX;
break;
case default:
DMode = GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH
}

@freddix

... and you should initialize DMode with some default value because you are using it.

... and you need a second "=" in:

Your case could also be simplified to an if:

@Gazelle
Effectively, second = added :p

I must not simplify cos, if some more modes are added to glut to handle RGB32, RGB24, RGB16 and color index 8 bits, I want to have just to add the correct flag to make my display mode use them.

@freddix

Make it like this:

@Gazelle
In fact, I've made it slightly different now:

@freddix
Quote:

The if() statement is wrong again and I'd do something more obvious like this:
BOOL IsSupported = CheckDisplayMode( Width, Height, Depth );
if ( IsSupported ) {
...

Again, a matter of style.

@ssolie
It's not wrong ... but it's not perfect ;)

@freddix

if ( Supported = TRUE ){

Yes this line is wrong, should be:

if ( Supported == TRUE ){

'==' compare some to a value.
'=' set some thing to a value.

If you type "if ( Supported = TRUE ){" then result of this is always TRUE, because "TRUE" is what "Supported" is set as, in side your if().

@LiveForIt
yes, it's what was explained before, I've understood, in the last statements, it was an error from me to not modify this in the post.

@freddix

In fact, you should never say "if (something == TRUE)" because that means it will only work for that one value (whatever "TRUE" is defined to be). "True" means any non-zero value.
The proper way to test for "truth" is: "if (something)..."

@tonyw: I only compare boolean to TRUE or FALSE. ;) I never compare to TRUE/FALSE for integer and others data ...

@freddix

What Tonyw was trying to say is that under C there is no such thing as a boolean type, in fact any numeric value can be interpreted as a boolean : 0 is false anything else is true.
So the BOOLEAN you are using is in fact an alias to a long and TRUE and FALSE are in fact two #defines.
is equivalent to and is equivalent to
However the first form has disadvantage in case of error in the equality test (that you did two times) of producing bugs (unless you are using the tip I told you to reverse the operands's order and I applied here) whereas the second has not (but for a beginner this form may seems a bit difficult to read)...

@abalaban

Quote:No, it's not. It's only the same if myVal is 1, not if myVal is for example 2.
Especially on AmigaOS that can be a problem since dos.library functions usually return DOSFALSE (0) or DOSTRUE (-1), not FALSE (0) or TRUE (1), and using would be wrong but works.

@abalaban

Quote:

No its not,

if( myVal)

is the same as typing:

if (myVal != 0)

any value not zero is true.

if( TRUE == myVal )

This line is only true if myVal is true, and as Joerg pointed out, TRUE is some times defined as -1 and some times as 1,
so its safer to write:

if (myVal)

Read about return values of OS functions in the OS4.X SDK and Linux man pages (clib/newlib) before you decide what to do.

@abalaban
Quote:
Since C99 there is a proper bool type in C (_Bool) but it has nothing to do with the fake boolean types that BOOL, BOOLEAN, etc. are. The stdbool.h header can be used to make the C _Bool type like the C++ bool type.

@ssolie

oops yes you'are right, I guess I have forgotten this.