beginner questions of2d arrays code example

Example 1: matrix c declaration

int disp[2][4] = { 10, 11, 12, 13, 14, 15, 16, 17};

Example 2: how to get input in 2d array in c

#include <stdio.h>

int main(){

    printf("Enter the number of columns");
    int i; 
    scanf("%d", &i);
    printf("Enter the number of rows");
    int y; 
    scanf("%d", &y);

    int r[i][y];
    int a;
    int b;

        for (a=0; a<i; a++){
            for (b=0; b<y; b++){
    scanf("%d",&r[a][b]);
        }
    }
}