在if条件下使用三元运算-目标C

Question

I am trying to check to find out whether or not numberOfItemsPerSection is bigger than 3 in the if condition. It always returns true. Then I decided to debug.

How is it possible that indexPath.row equals to 1 and numberOfItemsPerSection = 20 and it goes into to the if condition.

What am I doing wrong by using the following ternary operator?

if(indexPath.row == (numberOfItemsPerSection > 3) ? (numberOfItemsPerSection-4) : numberOfItemsPerSection)
{


}

Answer 1

Use parenthesises to resolve priority. Change the condition by below way. Just cover your turnery condition with parenthesis. It will resolve the turnery operator first and then it will compare it to indexPath.row.

if(indexPath.row == ((numberOfItemsPerSection > 3) ? (numberOfItemsPerSection-4) : numberOfItemsPerSection))

Answer 2

You can write:

if (indexPath.row == (numberOfItemsPerSection > 3 ? numberOfItemsPerSection - 4 : numberOfItemsPerSection)) { ... }

Or if you don't want to hurt your eyes:

BOOL desiredRow = numberOfItemsPerSection > 3 ? numberOfItemsPerSection - 4 : numberOfItemsPerSection;
if (indexPath.row == desiredRow) { ... }

Answer 3

NSInteger desiredRow = numberOfItemsPerSection > 3 ? (numberOfItemsPerSection-4) : numberOfItemsPerSection;
if(indexPath.row == desiredRow) { ... // do your coding }