Array Name

Array Name

1. What Array Name Really Is (beginner)

Array name = reference (address) of first box, NOT the boxes themselves. int[] a = new int[3] → a holds Heap address. Copying name copies address (both point to SAME boxes!).

2. Code — Reference Proof (exam favourite!)

int[] a = {10, 20, 30};
int[] b = a;      // copies ADDRESS (no new boxes!)
b[0] = 99;
System.out.println(a[0]); // 99! (same boxes — surprise!)
System.out.println(a);    // [I@1a2b3c (address, not elements!)
System.out.println(java.util.Arrays.toString(a)); // [99, 20, 30] (correct print!)

Passing array to method passes address → method changes original!

static void zero(int[] x) { x[0] = 0; }
zero(a); // a[0] becomes 0 (shared!)

3. Name vs Content

Code	Meaning
a	address of array
a[0]	first box value
a.length	box count
a == b	same address? (not same content!)
Arrays.equals(a,b)	same content? (correct compare!)

4. Traps

• System.out.println(a) prints gibberish address — use Arrays.toString(a).
• int a[] (C-style) works but int[] a (Java-style) preferred in exams.

5. Exam Points

• Reference diagram + b=a output — 5 marks, very frequent.
• Print with Arrays.toString — 2-3 marks, frequent.