Thread: gotos

Originally Posted by psychopath

Code:

void draw(){
    if(WeCantSeeTheObject()){
        goto skip;
    }

    /* rendering code */

skip: /*do nothing*/ ;

}

I've found this to be faster than using if/else to skip or run the drawing code for some reason. It was a while ago, so I could've done something else wrong.

There should be little difference betwen

Code:

if(!WeCantSeeTheObject()) {
    ... rendering code ... 
}

and the solution you posted. If there is, it's most likely because of the code generator in the compiler believes that the !WeCantSeeTheObject is not the same hit-rate as it really is (that is, the compiler is trying to optimize for a different rate of invisible objects than the code really has). But really, the code should be very close between those two cases.

gcc has a "predictor likelyhood" extension that can tell the compiler that something is likely or unlikely to he true - that way, the compiler can string together the likely variations in a straight line, and the unlikely ones out of line.

--
Mats

Except you can't use goto to jump from one function to another.

What does this print, and why?

Code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main ( ) {
    int a = 4;
    switch ( a  ) {
        case 1: case 2:
            printf("1 or 2\n" );
            break;
        case 3:
            printf("3\n" );
            break;
        defualt:
            printf("Something else\n");
            break;
    }
    return 0;
}

3\n
Something else\n

I do believe.

EDIT: Wait... that's just stupid. Ignore that. It'll print nothing, right? ... I feel intensely retarded today.
EDIT2: Well I've set MSVC to flag warnings as errors, unreferenced label.

Originally Posted by twomers

Default is misspelt ... so it'll err.

No, it won't. It will possibly warn that nothing is using defualt label, but it will compile. And it won't print anything since the default "default:" is an empty case.

--
Mats

Originally Posted by matsp

No, it won't. It will possibly warn that nothing is using defualt label, but it will compile. And it won't print anything since the default "default:" is an empty case.

--
Mats

Yup, something like that:

Code:

warning C4102: 'defualt' : unreferenced label
warning C4702: unreachable code
0 error(s), 2 warning(s)

There is no need for goto's. They're for people who haven't yet fully embraced structured programming concepts.

That's a big bump :\

Nothing a goto couldn't fix

Code:

/* ... */
    
    defualt:
        printf("Something else\n");
    break;
    
    default:
        goto defualt;
    break;
}
/* ... */

Doesn't really matter why it's bad, but it does matter that it is bad

Originally Posted by Rule #5

5. Don't bump threads. (Bumping: posting messages on threads to move them up the list or to post on a thread that has been inactive for two weeks or longer).

Naughty iMalc!