Rust array is fixed size. Can I modify its content?

Yes, you can modify the contents of a Rust array as long as it is declared as mutable using the mut keyword. However, while you can change the values of elements in the array, the size of the array remains fixed.

Example: Modifying an Array's Content

fn main() {
    // Declare a mutable array
    let mut numbers: [i32; 5] = [10, 20, 30, 40, 50];

    // Modify elements
    numbers[0] = 100; // Change the first element
    numbers[4] = 500; // Change the last element

    // Print the updated array
    println!("Modified array: {:?}", numbers);

    // Iterating and modifying elements
    for i in 0..numbers.len() {
        numbers[i] *= 2; // Double each element
    }

    // Print the updated array after iteration
    println!("Doubled array: {:?}", numbers);
}

Explanation:

1. Mutable Array Declaration:
   • Use let mut to allow modifications:
     let mut numbers: [i32; 5] = [10, 20, 30, 40, 50];
2. Modify Elements by Index:
   • Access elements using numbers[index] and assign a new value.
3. Iterating and Modifying:
   • Use a loop (for i in 0..numbers.len()) to traverse the array and modify its elements.

Output:

Modified array: [100, 20, 30, 40, 500]
Doubled array: [200, 40, 60, 80, 1000]

You cannot add or remove elements from a Rust array because its size is fixed. If you need dynamic resizing, use a vector (Vec<T>). However, for static collections, mutable arrays are efficient and sufficient for updating content.