C*

Pointers

Pointers, written T*, are used to refer to other objects in memory.

C* pointers are more like C++ references than C/C++ pointers: every operation on a pointer operates on the pointed-to value, except reassignment. Reassigning a pointer changes what the pointer points to.

Additionally, C* pointers cannot be null by default. To create nullable pointers, the pointer type has to be marked as nullable.

To form a pointer, the & operator can be used. To dereference a pointer, the * operator can be used.

Comparing pointers also compares to pointed-to objects. To compare the memory addresses, the reference equality operators === and !== can be used.

void main() {
    int i = 6;
    int* p = &i; // Make p point to i
    println(p); // Prints 6

    int* q = p; // Copy p to q, both point to i now
    println(p === q); // Prints true because both pointers point to the same memory address

    int j = 6;
    p = &j; // Change p to point to j
    println(p === q); // Prints false because pointers point to different memory addresses

    *p = 7; // Change the value of j
    println(p * q); // Multiplies the values pointed to by p and q, prints 42
}

Array pointers

Array pointers, written T[*], are pointers that point to an array of unknown length, or one step past the end of an array. They are the only pointer type that supports pointer arithmetic, since pointer arithmetic only makes sense for arrays.

void main() {
    int[3] a = [1, 2, 3];

    int[*] p = a; // p points to a
    println(p[0]); // prints 1

    p++; // increment pointer to next element
    println(p[0]); // prints 2

    p = &p[1]; // increment pointer to next element
    println(*p); // *p is equivalent to p[0], prints 3
}