Pointer to arrays-CodePudding

Could anyone tell me why the second and the last receive compile-time errors?

void test(){
    
    int array[10]{};

    int (*i) [10] = &array; // works
    int (*j) [10] = array;  // does not work
    int *k = array;     // works
    int *l = new int[10](); // works
    int (*m) [10] = new int[10]();      // does not work

    exit(0);
}

I'm not sure why the second does not work without the ampersand since array and &array refer to the same address. For the last, I think it's because it can't tell we're dynamically allocating an array specifically, but I'd like this confirmed.

CodePudding user response：

I'm not sure why the second does not work without the ampersand since array and &array refer to the same address. int (*j) [10] = array;

array decays to int* not int (*)[10] in several contexts. So even though the value of array and &array is same the types are different. The type of array before decaying is int [10] which decays to int* while the type of &array is int (*)[10].

So the error is telling you that we cannot initialize a int(*)[10](type on the left hand side) with an int*(type on the right hand side after decay).

error: cannot convert ‘int*’ to ‘int (*)[10]’ in initialization

Similarly in the last case int (*m) [10] = new int[10]() the type on the right hand side is int* which cannot be used to intialize the type on the left hand side(int (*)[10]).