Shifting Elements in Arrays (AP CSA)

Shifting means moving elements left or right within an array. Since arrays are fixed-size, shifting doesn’t resize — it overwrites. The direction determines your loop order.

Shift Left (remove-style)

Move each element one position to the left. Traverse forward (low to high index).

int[] arr = {10, 20, 30, 40, 50};

// Shift everything left by 1
for (int i = 0; i < arr.length - 1; i++) {
    arr[i] = arr[i + 1];
}
arr[arr.length - 1] = 0;  // clear last slot

// Result: [20, 30, 40, 50, 0]

Shift Right (insert-style)

Move each element one position to the right. Traverse backward (high to low index) to avoid overwriting.

// Shift everything right by 1 (starting from index 1)
for (int i = arr.length - 1; i > 0; i--) {
    arr[i] = arr[i - 1];
}
arr[0] = 0;  // clear first slot

// Result: [0, 10, 20, 30, 40]

int[] arr = {1, 2, 3, 4, 5};
for (int i = 0; i < arr.length - 1; i++) {
    arr[i] = arr[i + 1];
}
arr[arr.length - 1] = 0;