Check if NSInteger is odd or even

Question

I am trying to check if NSInteger is odd or even. I found a way to do this using C, but it does not work with Objective-C. How should I do it?

Answer 1

NSInteger defined as int (or long in some environments). Thus, the odd check is similar to a regular int:

 NSInteger num; if (num % 2) // odd else // even 

Answer 2

 NSInteger n = 5; NSLog(@"%s", n & 1 ? "odd" : "even"); 

or using if

 if (n & 1) { ; // odd } else { ; // even } 

with some output:

 if (n & 1) { NSLog(@"odd"); } else { NSLog(@"even"); } 

pointer example:

 NSInteger x = 7; NSInteger *y = &x; if (*y & 1) { NSLog(@"odd"); } else { NSLog(@"even"); } 

Answer 3

As I know. NSInteger , unlike NSNumber , is just a typer for a real integer type in rows:

 typedef long NSInteger; 

So you should be able to:

 NSInteger nsintvar = 77; if ((nsintvar % 2) == 0) { // number is even } else { // number is odd } 

---

Here is the complete program compiled under Cygwin with GNUstep, which illustrates this:

 #import <stdio.h> #import <Foundation/NSObject.h> int main( int argc, const char *argv[] ) { NSInteger num; for (num = 0; num < 20; num++) { if ((num % 2) == 0) { printf ("%d is even\n", num); } else { printf ("%d is odd\n", num); } } return 0; } 

It outputs:

 0 is even 1 is odd 2 is even 3 is odd 4 is even 5 is odd 6 is even 7 is odd 8 is even 9 is odd 10 is even 11 is odd 12 is even 13 is odd 14 is even 15 is odd 16 is even 17 is odd 18 is even 19 is odd 

Answer 4

These other answers should work. Maybe this is a problem with your makefile or something else. Think about what part of the code.

If all else fails, just declare the integer as int. You do not need to declare it as an NSInteger.

Answer 5

Use the operator "%". Essentially, it works on the remainder when you divide the number. So:

number% 2

It would be = 0 if the number were even, since an even number divided by 2 has no remainders. If it is not 0, it must be odd.

Answer 6

 NSArray *arrayTotal = [NSArray arrayWithObjects:@"A", nil]; // NSArray *arrayTotal = [NSArray arrayWithObjects:@"A", @"B", nil]; // NSArray *arrayTotal = [NSArray arrayWithObjects:@"A", @"B", @"C", nil]; // NSArray *arrayTotal = [NSArray arrayWithObjects:@"A", @"B", @"C", @"D", nil]; // NSArray *arrayTotal = [NSArray arrayWithObjects:@"A", @"B", @"C", @"D", @"E", nil]; NSArray *arrLeft; NSArray *arrRight; NSRange range; range.location = 0; range.length = ([arrayTotal count] % 2) ? ([arrayTotal count] / 2) + 1 : ([arrayTotal count] / 2); arrLeft = [arrayTotal subarrayWithRange:range]; range.location = range.length; range.length = [arrayTotal count] - range.length; arrRight = [arrayTotal subarrayWithRange:range]; NSLog(@"Objects: %lu", (unsigned long)[arrLeft count]); NSLog(@"%@", [arrLeft description]); NSLog(@"Objects: %lu", (unsigned long)[arrRight count]); NSLog(@"%@", [arrRight description]); 

Hope this helps !!!