XCode警告“表达式结果未使用”的数学陈述

Question

I am getting a warning while doing this

CGFloat viewHeight = ([self.quotaArray count]*kROW_HEIGHT) + kHEADER_HEIGHT + kFOOTER_HEIGHT;

Basically this math statement returns me the height of my table view, which is the

(number of rows * row height) + header height + footer height

What am I doing wrong?

Answer 1

My guess: You have something like:

#define kHEADER_HEIGHT 3;

So, the line of code you give turns into:

CGFloat viewHeight = ([self.quotaArray count]*1) + 3; + 2;

Which is valid; the last part produces a warning. ( +2 is a valid expression, which does nothing but produce the value 2, hence the warning.)

So, remove the semicolon from your define, or, even better, stop using #define when a static const int would do. (Because you can't get crazy errors like this if you're just using an int.)

Answer 2

Are you using the variable after it? That warning is telling you that you created a CGFloat called viewHeight and not using it in your code