数组中的替换值

let arr = [1, 2, 3, 4, 5];
arr[2] = 10; // 按索引替换
console.log(arr); // 输出: [1, 2, 10, 4, 5]

arr = arr.map(x => x === 4 ? 20 : x); // 按条件替换
console.log(arr); // 输出: [1, 2, 10, 20, 5]

arr = [1, 2, 3, 4, 5]
arr[2] = 10  # 按索引替换
print(arr)   # 输出: [1, 2, 10, 4, 5]

arr = [20 if x == 4 else x for x in arr]  # 按条件替换
print(arr)   # 输出: [1, 2, 10, 20, 5]

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5};
        arr[2] = 10; // 按索引替换
        System.out.println(Arrays.toString(arr)); // 输出: [1, 2, 10, 4, 5]

        for (int i = 0; i < arr.length; i++) {
            if (arr[i] == 4) arr[i] = 20; // 按条件替换
        }
        System.out.println(Arrays.toString(arr)); // 输出: [1, 2, 10, 20, 5]
    }
}

let arr = [1, 2, 3];
let index = 5;
if (index >= 0 && index < arr.length) {
    arr[index] = 10;
} else {
    console.log("索引越界");
}

arr = [1, 2, 3, 4, 5]
arr = [20 if x == 3 else x for x in arr]  # 正确的条件应该是 x == 3 而不是 x == 4
print(arr)   # 输出: [1, 2, 20, 4, 5]