How many ways can you assign initial values to a two-dimensional array?

How many ways can you assign initial values to a two-dimensional array
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Method 1

• Branch to initial value of two-dimensional array ：

int arr[3][4]={{1,2,3,4},{5,6,7,8},{9,10,11,12}};

This assignment method is simple and intuitive , Give the value of the first curly bracket to the first line , One analogy .

ask ：arr[2][0]=?
answer ：9

Method 2

• Assign values to the elements in the order of the array ：

int arr[3][4]={1,2,3,4,5,6,7,8,9,10,11,12};

shortcoming ： If there's more data , Easy to miss , Inconvenient to check .

ask ：arr[1][2]=?
answer ：7

Method 3

• Assign values to some elements

int arr[3][4]={{1},{5},{9}};

The element without initial value is... By default 0.
advantage ： It is applicable to the situation with more data and more zeros , There is no need to mark every zero , Just input a small amount of data .

ask ：arr[2][3]=?
answer ：0

Method four

• When assigning initial values to all elements , The length of the first dimension can be omitted , The system will judge the length of the second dimension according to the total number of data , But the length of the second dimension cannot be omitted .

int arr[][4]={1,2,3,4,5,6,7,8,9,10,11,12}

The system will allocate storage space according to the total number of data , altogether 12 Data , Each row 4 Column , Of course, it can be determined as 3 That's ok .

ask ：arr[2][2]=?
answer ：11

Method five

• When assigning initial values to some elements , The length of one dimension can also be omitted , But the initial value needs to be assigned to the branch .

int arr[][4]={{1,2,3,4},{},{9,10,11,12}};

ask ：arr[1][2]=?
answer ：0