取数组前三个

arr = [1, 2, 3, 4, 5]
first_three = arr[:3]
print(first_three)  # 输出: [1, 2, 3]

let arr = [1, 2, 3, 4, 5];
let firstThree = arr.slice(0, 3);
console.log(firstThree);  // 输出: [1, 2, 3]

import java.util.Arrays;

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

#include <iostream>
#include <vector>

int main() {
    std::vector<int> arr = {1, 2, 3, 4, 5};
    std::vector<int> firstThree(arr.begin(), arr.begin() + 3);
    for (int num : firstThree) {
        std::cout << num << " ";  // 输出: 1 2 3
    }
    return 0;
}

arr = [1, 2]
if len(arr) >= 3:
    first_three = arr[:3]
else:
    first_three = arr
print(first_three)  # 输出: [1, 2]

arr = [1, 2, 3, 4, 5]
first_three = [next(arr_iter) for _ in range(3)]
print(first_three)  # 输出: [1, 2, 3]