Why can’t I initialize a variable-sized array?

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  • The size of the array must be a constant integral expression.
  • An integral literal is a constant integral expression. (int arr[5];)

  • A constant integral variable initialized with a constant expression is a constant expression. (const int j = 4; const int i = j; int a[i];)

  • A constant variable initialized with a non-constant expression is not a constant expression

     int x = 4;  // x isn't constant expression because it is not const
 const int y = x; //therefore y is not either
 int arr[y]; //error)

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