C language----array (describe array-related knowledge, dynamically create a two-dimensional array)

Interview Question: What is an Array?

Answer such questions in a step-by-step, organized manner.

①Concept : An array is a collection of data of the same type ;

②Classification : one-dimensional array, two-dimensional array

③Features : The array is a continuous space at the bottom layer , which supports random access.
Array names have different meanings in different contexts. & array name, sizeof (array name) all represent the entire array , in other cases (as parameters, pointers, etc.) represent the address of the first element .
Note: the type of int arr[10] is int[10].
One-dimensional array

Two-dimensional array

④Initialization Array initialization can be a given number of elements , or it can be indefinite , it can be completely initialized , or it can be incompletely initialized . int array[10] = { 0 }; int array[] = { 0 }; int array[10] = { 1, 2, 3 }; int array[5] = { 1, 2, 3, 4, 5 } ; int array[][4]={0};

⑤Usage : a. storage element ; b. parameter transfer ; c. as function return value

⑥Note : the out-of-bounds access of the array int
a = 0;
int array[5] = { 0, 1, 2, 3, 4 };
storage of variables in memory in the above example:

there are four protections before and after each variable bytes.
Row access is more efficient than column access.

Let's look at an example:

int i = 0;
int a[10] = {};
for (; i <= 12; i++)
{
    a[i] = 0;
}

Can the above program work normally? What can go wrong?
Infinite loop . Memory analysis:

Interview question: Dynamically create a two-dimensional array and consider how to destroy it?

#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
#define ROW 3
#define COLUMN 4
int main()
{
    int i, j;
    int(*p)[COLUMN];
    p = (int(*)[COLUMN])malloc(ROW*COLUMN*sizeof(int));
    for (i = 0; i < ROW; i++)
    {
        for (j = 0; j < COLUMN; j++)
        {
            p[i][j] = rand() % 10;
        }
    }
    for (i = 0; i < ROW; i++)
    {
        for (j = 0; j < COLUMN; j++)
        {
            printf("%d ", p[i][j]);
        }
        printf("\n");
    }
    free(p);
    system("pause:");
    return 0;
}