Initialization of variables sized arrays in C

The C99 standard allows variable sized arrays (see this). But, unlike the normal arrays, variable sized arrays cannot be initialized.

For example, the following program compiles and runs fine on a C99 compatible compiler.

#include<stdio.h> 
  
int main() 
{ 
  int M = 2; 
  int arr[M][M]; 
  int i, j; 
  for (i = 0; i < M; i++) 
  { 
    for (j = 0; j < M; j++) 
    { 
       arr[i][j] = 0; 
       printf ("%d ", arr[i][j]); 
    } 
    printf("\n"); 
  } 
  return 0; 
} 

Output:

0 0
0 0

But the following fails with compilation error.

#include<stdio.h> 
  
int main() 
{ 
  int M = 2; 
  int arr[M][M] = {0}; // Trying to initialize all values as 0 
  int i, j; 
  for (i = 0; i < M; i++) 
  { 
    for (j = 0; j < M; j++) 
       printf ("%d ", arr[i][j]); 
    printf("\n"); 
  } 
  return 0; 
} 

Output:

Compiler Error: variable-sized object may not be initialized

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