Equation not working???

Frankie · 08-03-2009, 01:36 AM

I use this to do a simple calculation but it won't work. Keeps bringing up 0.00

Code:

float tipTotal = tipSelected * 3.8 / [billTotal.text floatValue];
tipAmount.text = [NSString stringWithFormat:@"%.2f", tipTotal];

But this works....

Code:

float tipTotal = [billTotal.text floatValue] / tipSelected * 3.8 ;
tipAmount.text = [NSString stringWithFormat:@"%.2f", tipTotal];

I need it the first way though. What am I doing wrong???

**smasher** · 08-03-2009, 02:03 AM

What type is tipSelected, and what is its value? if it's value is less than one, then tipTotal will be much smaller then one cent, and will get rounded to 0.00 by your %.2f. Your first set of code seems to give the mathematically "correct" answer if I plug in 10 and 50.

Code:

	int tipSelected = 10;
	float subtotal = 50.00
	float tipTotal = tipSelected * 3.8 / subtotal;    
	NSLog(@"tipTotal: %f", tipTotal);

I don't really understand your code or what you're calculating though; what is the 3.8 for, and why are you dividing by the bill amount?