Thread: If statements

I'm having some trouble figuring out if statements, they've been very finicky. Can anyone detect the problem with this? Or, alternately, can anyone say whether the if if-else else method I am using is a good one, or if I should switch to something else (no pun intented).

Thanks

Code:

		/* X-Axis Groups */
		float VerSet_r_A; /*X Dimension of Vertices 0,2,4,6 */
		float VerSet_r_D; /*X Dimension of Vertices 1,3,5,7 */
		
		/* Y-Axis Groups */
		float VerSet_r_B; /*Y Dimension of Vertices 0,1,6,7 */
		float VerSet_r_E; /*Y Dimension of Vertices 2,3,4,5 */
		
		/* Z-Axis Groups */
		float VerSet_r_C; /*Z Dimension of Vertices 0,1,2,3 */
		float VerSet_r_F; /*Z Dimension of Vertices 4,5,6,7 */
		
		int C_closer; // Value 1 = C is closer. Value 0 = F is closer.
		int A_right; // Value 1 = A is right. Value 0 = D is right.
		int B_up; // Value 1 = B is up. Value 0 = E is up.
		
		int Config_Case; // 0 = P, 1 = S, 2 = R, 3 = Q

int main (void) {
		if(VerSet_r_C > 0)
			{
				printf("Real_Cube is out of camera view. Real_Z value must be less than zero. \n");
				return(0);
			};
			
		if(VerSet_r_F > 0)
			{
				printf("Real_Cube is out of camera view. Real_Z value must be less than zero. \n");
				return(0);
			};
			
		if(VerSet_r_C > VerSet_r_F)
			C_closer = 1; // true	
		else
			C_closer = 0; // false

		if(VerSet_r_A > VerSet_r_D)
			A_right = 1; // true	
		else 
			A_right = 0; // false	
			
		if(VerSet_r_B > VerSet_r_E)
			B_up = 1;	// true
		else 
			B_up = 0;	// false
			
		if(C_closer == 1) {
			if(A_right == 0) {
				if(B_up == 0) {
					Config_Case = 0;
				}
				else 
				printf("Real_Cube Case orientation check error.");
				return(0);
			}
			else if(A_right == 1) {
				if(B_up == 1) {
					Config_Case = 1;
				}
				else 
				printf("Real_Cube Case orientation check error.");
				return(0);
			}
			else
				printf("Real_Cube Case orientation check error.");
				return(0);
		}
		else if(C_closer == 0) {
			if(A_right == 0) {
				if(B_up == 1) {
					Config_Case = 2;
				}
				else 
				printf("Real_Cube Case orientation check error.");
				return(0);
			}
			else if(A_right == 1) {
				if(B_up == 0) {
					Config_Case = 3;
				}
				else 
				printf("Real_Cube Case orientation check error.");
				return(0);
			}
			else
				printf("Real_Cube Case orientation check error.");
				return(0);			
		}
/* For variable "Config_Case": Integer Values: Case-P = 0, Case-S = 1, Case-R = 2, Case-Q = 3 */
/* End Real_Cube Orientation Determination */			

/* Main generation procedure? */

//For now, we are going to deal only with Case-P, and fill the others in later.
		printf("Case is: %i \n",Config_Case);

if(Config_Case = 0) {
	printf("okay, we made it this far. \n");
}
else
	printf("We can only deal with Case-P Real_Cube orientations at the moment. \n");
	return(0);

/* END OF PROGRAM. */
return(0);
};

Notes: This

Code:

if(VerSet_r_C > VerSet_r_F)
			C_closer = 1; // true	
		else
			C_closer = 0; // false

is the same as

Code:

C_closer = (VerSet_r_C > VerSet_r_F);

The boolean expression on the right will always return 0 or 1.

Similarly, I wouldn't test

Code:

if (C_closer == 1)

but just

Code:

if (C_closer)

(it "says what you mean"), and certainly you don't need to test it again in the else-clause. (If you're there, you know C_closer is 0.)

You can maybe get away with some condensing on the inner loops -- for example, if C_closer is 1, then what we really care about is that A_right and B_up are the same; I might write that part something like this:

Code:

.
.
.
if (C_closer) {
    if (A_right != B_up) {  /* axes not positioned correctly */
        printf("Real_Cube Case orientation check error.");
        return(0);
    }
    /* if we're here, we're correct, so let's cheat a little */
    Config_Case = A_right;
}
.
.
.

but as noted that's cheating.

Thanks.

What do I do in cases where C_closer is false?

Code:

if (C_closer == 1)

Code:

if (C_closer)

something to replace:

Code:

if (C_closer == 0)

in a direct way.

thanks

Normally if C_closer has boolean semantics (that is, you're thinking of it as a true-false expression), then the obvious way to do it is

Code:

if (!C_closer)

Of course, here you shouldn't test C_closer is 0 at all (at least not in the snippet you posted), since when you get to the else clause C_closer has to be 0 (why test for something you know is true?).

Hey, thanks. I'm loosing my mind though... I can't figure out what is going on here.
My code was running last night, as was another program referenced at: http://cboard.cprogramming.com/showthread.php?t=99807
But now, each of them builds. But when I run, it goes straight to logout.

What is that about? Can there be some outside force? Tried restarting the computer. working on xcode on os 10.5.2