sizeof求数组长度

 	int arr1[10]={1,2,3,4};
 	int arr2[]={1,2,3,4};
 	int len1 = sizeof(arr1)/sizeof(arr1[0]);//10
 	int len2 = sizeof(arr2)/sizeof(arr2[0]);//4

	char arr1[10][30]={"aaaaaa","1111","00000000","AAAAA"};
	int len = sizeof(arr1)/sizeof(arr1[0]);//10

	char arr2[][30]={"aaaaaa","1111","00000000","AAAAA"};
	int len2 = sizeof(arr2)/sizeof(arr2[0]);//4