How to check if array is null or empty?

Question

I want to check if my array is empty or null, and on base of which I want to create a condition for example.

if(array ==  EMPTY){
//do something
}

I hope I'm clear what I am asking, just need to check if my array is empty?

regards

score 114 · Accepted Answer · answered Oct 18 '10 at 13:03

114

if (!array || !array.count){
  ...
}

That checks if array is not nil, and if not - check if it is not empty.

answered Oct 18 '10 at 13:03

Vladimir

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5

It works but it's not completely flawless: `array.count` should be `[array count]` since you're not dealing with a property (var) here. – Rengers Oct 18 '10 at 17:15
6

Nope -- `array.count` is just fine in that context. Syntactically, anyway. Stylistically? No particular standard is recommended at this time. – bbum Oct 18 '10 at 17:22
4

this is the same as `if (!array.count)` – user102008 Apr 18 '12 at 01:20
2

I think the weight of stylistic opinion is against dot notation for calling generic methods on an object, so I'm with @Rengers on this one. – davidf2281 May 09 '13 at 11:51
1

For the sake of accuracy @Rengers and @davidf2281, NSArray.h declares count as a property `@property (readonly) NSUInteger count;` – nicktmro Apr 21 '15 at 03:57
For those, !array.count----> is giving this error-[NSNull count]: unrecognized selector sent to instance, try @Sachin's array == (id)[NSNull null] – mavericks Oct 06 '15 at 11:58

score 29 · Answer 2 · edited Nov 06 '15 at 11:06

if ([array count] == 0)

If the array is nil, it will be 0 as well, as nil maps to 0; therefore checking whether the array exists is unnecessary.

Also, you shouldn't use array.count as some suggested. It may -work-, but it's not a property, and will drive anyone who reads your code nuts if they know the difference between a property and a method.

UPDATE: Yes, I'm aware that years later, count is now officially a property.

score 12 · Answer 3 · edited Nov 06 '15 at 11:09

12

you can try like this

if ([array count] == 0)

edited Nov 06 '15 at 11:09

Pawan Rai

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answered Oct 18 '10 at 13:03

Vanya

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quarac · Answer 4 · 2018-09-28T11:01:50.623

9

Best performance.

if (array.firstObject == nil)
{
    // The array is empty
}

The way to go with big arrays.

edited Sep 28 '18 at 11:01

answered Dec 04 '14 at 17:59

quarac

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3

best answer. the others suggest to use `count` property, which implies enumerating the array and can be a performance issue with big arrays – boweidmann May 14 '18 at 13:25
I prefer this way as well, because we don't actually care about the exact count when we just want to check whether array is empty. – Kjuly Jul 15 '21 at 00:36

score 9 · Answer 5 · answered Oct 18 '10 at 13:05

9

Just to be really verbose :)

if (array == nil || array.count == 0)

answered Oct 18 '10 at 13:05

willcodejavaforfood

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score 4 · Answer 6 · edited Nov 10 '15 at 08:19

4

if (array == (id)[NSNull null] || [array count] == 0) {
    NSLog(@"array is empty");
}

edited Nov 10 '15 at 08:19

itsji10dra

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answered Jan 03 '13 at 07:56

SachinVsSachin

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score 3 · Answer 7 · edited May 23 '17 at 11:33

Swift 3

As in latest version of swift 3 the ability to compare optionals with > and < is not avaliable

It is still possible to compare optionals with ==, so the best way to check if an optional array contains values is:

if array?.isEmpty == false {
    print("There are objects!")
}

as per array count

if array?.count ?? 0 > 0 {
    print("There are objects!")
}

There are other ways also and can be checked here link to the answer

score 2 · Answer 8 · answered Jan 03 '13 at 07:45

2

As nil maps to 0, which equals NO, the most elegant way should be

if (![array count])

the '==' operator is not necessary.

answered Jan 03 '13 at 07:45

Brian

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score 1 · Answer 9 · answered May 09 '13 at 09:05

1

You can also do this kind of test using if (nrow>0). If your data object is not formally an array, it may work better.

answered May 09 '13 at 09:05

conservationista

11
1

score 1 · Answer 10 · answered May 09 '13 at 09:37

1

null and empty are not the same things , i suggest you treat them in differently

if (array == [NSNull null]) {
    NSLog(@"It's null");
} else if (array == nil || [array count] == 0) {
     NSLog(@"It's empty");
}

answered May 09 '13 at 09:37

JasonLee

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5

Could you please brief the difference between both the conditions, in what case which one would call? – mavericks Oct 06 '15 at 12:00

score 0 · Answer 11 · edited Apr 27 '17 at 11:34

0

if (array == nil || array.count == 0 || [array isEqaul [NSNull Null]])

edited Apr 27 '17 at 11:34

Uma Madhavi

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answered Apr 18 '17 at 08:52

saurabh rathod

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score 0 · Answer 12 · edited Jul 17 '19 at 05:38

0

In Swift 4

if (array.isEmpty) {
    print("Array is empty")
}
else{
    print("Array is not empty")
}

edited Jul 17 '19 at 05:38

Harshal Bhavsar

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answered Dec 05 '18 at 07:49

Raghib Arshi

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How to check if array is null or empty?

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