Dynamic Array allocation in C ++

I have never understood why new can be used to dynamically allocate arrays. Today I finally figured it out. UpperCode

Int Main ()
{
Int A = 5 ;
Int Len [a]; // Error
Return   0 ;
}

In this case, an error is reported, indicating that the array parameter is not a constant. It must be changed to const int A = 5.

If new is used, the array size can be dynamically defined without the constant parameter.

Int Main ()
{
Int A = 5 ;
Int   * B = New   Int [A]; // OK
Return   0 ;
}