判断一个数组的元素是否在另一个数组里

可以使用循环和条件判断来判断一个数组的元素是否在另一个数组里。

Python代码示例：

arr1 = [1, 2, 3, 4, 5]
arr2 = [3, 5, 7, 9]

for i in arr1:
    if i in arr2:
        print(i, "is in arr2")
    else:
        print(i, "is not in arr2")

输出：

1 is not in arr2
2 is not in arr2
3 is in arr2
4 is not in arr2
5 is in arr2

另外，还可以使用Python的set类型来判断两个数组是否有交集：

arr1 = [1, 2, 3, 4, 5]
arr2 = [3, 5, 7, 9]

set1 = set(arr1)
set2 = set(arr2)

if set1.intersection(set2):
    print("There are common elements in arr1 and arr2")
else:
    print("There are no common elements in arr1 and arr2")

输出：

There are common elements in arr1 and arr2