delphi - Translation check from C++ to ObjectPascal which is better -

i translating c++ code objectpascal (first time), , c++ still new me.

the c++ header file looks this:

class renumfd { public:     renumfd(int length);     ~renumfd();     void compfd(double *buff);  //...other public functions cut space  private:     void rmfd(int n, int isgn, double *a, int *ap, double *kw);  //...other private functions cut space      int _length;     int *_ap;     double *_kw; } 

i have translated them way:

type  trenumfd = class  private    _length: integer;    _ap: pinteger;    _kw: pdouble;    procedure rmfd(n:integer; isgn:integer; var a:double; var ap:integer; var kw:double);  //... other procedures cut space     public   constructor create(const length:integer);   destructor  destroy(); override;   procedure compfd(var buff:double); end; 

i read pointers used parameters in c++ should set var parameters in object pascal. correct, or should stick more literal translation (worried being bitten later).

also in c++ constructor there following code, unsure in 1 line.

renumfd::renumfd(int length) {     _length = length;     _ap = new int[2 + (1 << ((int)(log(2.0 + length) + 0.5) / 2))];     _ap[0] = 0;  <-- setting pointer nil, or assigning 0?      //...  } 

i unsure if should translate line in object pascal filling first element 0 or assigning nil:

_ap := allocmem(2 + (1 shl (trunc(ln(2.0 + length) + 0.5) / 2))) * sizeof(integer)); _ap := nil; 

maybe trying hard guess intent?

the decision use var or pointer depends on how going used, , whether can set nil or not. typically var better, pointer has uses. did not provide enough code show decision best.

as array allocation, dynamic array better choice allocmem():

type   renumfd = class   public     constructor create(length: integer);     //...       private     _ap: array of integer;     //...   end; 

constructor renumfd.create(length: integer); begin   setlength(_ap, 2 + (1 shl (trunc(log(2.0) + 0.5) div 2)));   _ap[0] := 0; // <-- assigns 0 first integer in array   //... end;