armanriazi rust error E0502 cannot borrow `s` as mutable because it is also borrowed as immutable

The error message "E0502 cannot borrow s as mutable because it is also borrowed as immutable" in Rust typically occurs when you try to borrow a variable as mutable while it is already borrowed as immutable. This violates Rust's borrowing rules, which ensure memory safety and prevent data races.

To resolve this error, you need to ensure that you don't have any other references to the variable s when you try to borrow it as mutable. Make sure that all previous borrows of s are released before attempting to borrow it mutably.

Here's an example that demonstrates the error and a possible solution:

fn main() {
    let s = String::from("Hello");

    let reference = &s; // Immutable borrow

    // Attempting to borrow `s` as mutable while it is still borrowed immutably
    let mutable_reference = &mut s; // Error: E0502

    println!("{}", s);
}

To fix the error, you can simply remove the immutable borrow before attempting to borrow s as mutable:

fn main() {
    let mut s = String::from("Hello");

    let reference = &mut s; // Mutable borrow

    println!("{}", s);
}

By ensuring that there are no active borrows of s when you try to borrow it mutably, you can avoid the "E0502 cannot borrow s as mutable because it is also borrowed as immutable" error.

I hope this helps! Let me know if you have any further questions.