Does objective-c follow the order of operations (B

问题:

I'm just wondering, because the app I built does a pretty long equation, and the result is a different than when it's done on an Excel spreadsheet, where I got the equation. The difference gets higher the higher the input numbers are. Here is the equation that I entered in xcode:
360 * num1 * num3 * (1 - powf(14.9 / num1, 0.286))
(num1 and num3 are the input numbers).
Here is the Excel calculation:
=360*R9*R11*(1-((R10/R9)^0.286))
(R9 is equal to num1, and R11 is equal to num3 and R10 is 14.9)

I don't see a difference in the equations, but if you do, please point it out. My quess it one of the two (probably the ob-c one) is doing something different than what I expected.

回答1:

Yes. Objective-C is a superset of C.

So all the features that C has, Objective-C has as well.

 360 * num1 * num3 * (1 - powf(14.9 / num1, 0.286)) (num1 and num3 are the input numbers)
          A * num3 * (1 - powf(14.9 / num1, 0.286)) 
                 B * (1 - powf(14.9 / num1, 0.286)) 
                 B * (1 - powf(C, 0.286)) 
                 B * (1 - D) 
                 B * (E) 
                      F 

And just for information, BEDMAS is not fully followed. If D & M are there at same level, the left most will be evaluated first, and so is the rule for A & S. However this does not look big deal, but when it comes to truncation and rounding with decimal numbers it creates a big problem.

a * b / c is calculated  as "(a*b) / c" 

whereas

a / b * c is calculated as "(a/b) * c"