已知数组定义为```cpp int arr[] = {1,2,3,4,5};
for(int i=0; i<=5; i++) cout << arr[i] << " ";
for(int i=0; i<sizeof(arr)/sizeof(arr[0]); i++) cout << arr[i] << " ";
int i=0; while(i<5) { cout << arr[i] << " "; }
for(int num : arr) { cout << num << " "; break; }