Array type 'int [16]' is not assignable

Question

I'm developing an iOS application with latest SDK.

I want to do this on a .mm file:

@interface MyClass ()
{
   int _cars[16];

   ...
}

@end

@implementation MyClass

-(id)init
{
    self = [super init];

    if (self)
    {
        _cars = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
    }

    ...
}

But I get the following error:

Array type 'int [16]' is not assignable

How can I fix this error?

zoul · Accepted Answer · 2013-03-04T18:10:48.403

12

If you just want to initialize the array:

int _cars[16] = {0};

It’s safe to drop the extra zeros, the compiler will figure them out. It’s not possible to assign whole arrays in C, that’s why the compiler complains in your case. It’s only possible to initialize them, and the assignment is only considered to be initialization when when done as a part of the declaration.

edited Mar 04 '13 at 18:10

answered Mar 04 '13 at 18:04

zoul

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If the array is an instance variable, it should be initialized to zero automatically by the `alloc` method (see [this question](http://stackoverflow.com/questions/990817/are-ints-always-initialized-to-0)). Take a look at the array contents to make sure. – zoul Mar 05 '13 at 07:15

score 9 · Answer 2 · answered Mar 04 '13 at 18:05

9

Objective-C++ is no different from C, Objective-C, or C++ in this case. You have to initialize an array when you declare it:

int _cars[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

Arrays aren't assignable lvalues.

answered Mar 04 '13 at 18:05

Carl Norum

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But I can't do that on @interface. – VansFannel Mar 05 '13 at 07:07
You don't need to if it's an instance variable. It will be zero initialized by default. – Carl Norum Mar 05 '13 at 07:15

Array type 'int [16]' is not assignable

2 Answers2