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
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12 Answers
if (!array || !array.count){
...
}
That checks if array is not nil, and if not - check if it is not empty.
6 Comments
Rengers
It works but it's not completely flawless:
array.count should be [array count] since you're not dealing with a property (var) here.
bbum
Nope --
array.count is just fine in that context. Syntactically, anyway. Stylistically? No particular standard is recommended at this time.
user102008
this is the same as
if (!array.count)
davidf2281
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. <cowers in a corner waiting for holy war>
nicktmro
For the sake of accuracy @Rengers and @davidf2281, NSArray.h declares count as a property
@property (readonly) NSUInteger count; |
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.
Comments
you can try like this
if ([array count] == 0)
Comments
Just to be really verbose :)
if (array == nil || array.count == 0)
answered Oct 18, 2010 at 13:05
willcodejavaforfood
44.2k17 gold badges83 silver badges111 bronze badges
Comments
Best performance.
if (array.firstObject == nil)
{
// The array is empty
}
The way to go with big arrays.
2 Comments
boweidmann
best answer. the others suggest to use
count property, which implies enumerating the array and can be a performance issue with big arrays
Kjuly
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.
if (array == (id)[NSNull null] || [array count] == 0) {
NSLog(@"array is empty");
}
Comments
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
Comments
As nil maps to 0, which equals NO, the most elegant way should be
if (![array count])
the '==' operator is not necessary.
Comments
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.
Comments
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");
}
1 Comment
mavericks
Could you please brief the difference between both the conditions, in what case which one would call?
if (array == nil || array.count == 0 || [array isEqaul [NSNull Null]])
Comments
In Swift 4
if (array.isEmpty) {
print("Array is empty")
}
else{
print("Array is not empty")
}
