How to declare a string outside the function but define it's size inside?

[ihato]

//HERE!
int main(){
   int N = 6;
   char S[N]; //I don't want this here, but up there (where "HERE!" is)
   return 0;
}

I could just do:

char* S;
int main(){
   int N = 6;
   S = new char[N];
   return 0;
}

But I want this to do without dynamic memory (Don't ask why).
Is there a way?

[Dy7SLyTq]

you can do it c-style: extern S[]