如何从方法内部更改外部变量的值

public class Main {
    public static void main(String[] args) {
        int[] arr = {1, 2, 3};
        changeArray(arr);
        System.out.println(Arrays.toString(arr)); // 输出 [4, 5, 6]
    }
    
    public static void changeArray(int[] arr) {
        arr[0] = 4;
        arr[1] = 5;
        arr[2] = 6;
    }
}

def change_value(value):
    return value + 1

num = 10
num = change_value(num)
print(num)  # 输出 11

#include <iostream>

int num = 10;

void changeValue() {
    num = 20;
}

int main() {
    std::cout << num << std::endl;  // 输出 10
    changeValue();
    std::cout << num << std::endl;  // 输出 20
    return 0;
}