unusual C++ constructor

Asked Jun 16 '18 at 08:16

Active Jun 16 '18 at 08:16

Viewed 33 times

class ClassB{
public:
  ClassB(ClassA *_a) : a(_a), f1(NULL), f2(NULL)
      {if(!myListObj) myListObj= new myList;};

static myList *myListObj;

protected:

  ClassA *a;
  float *f1;
  float **f2;
};

The constructor looks weird. I have never seen such constructor signature. It looks like, it is taking only one parameter, an object "a" which is ClassA type pointer, but then there is f1 and f2 set as null. How f1 and f2 is added and how can a float type pointer be set as NULL?

Can anyone please help me understand the following part of the code-

ClassB(ClassA *_a) : a(_a), f1(NULL), f2(NULL)
          {if(!myListObj) myListObj= new myList;};

asked Jun 16 '18 at 08:16

Natasha

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What about `float *f1 = NULL;` does this look ok? This is basically what `f1(NULL)` does. – Killzone Kid Jun 16 '18 at 08:20
1

also use `nullptr` instead of `NULL` – Joseph D. Jun 16 '18 at 08:21
`:` is OK, but if you inadvertently insert `;` in that place, you'll get compiler errors - it's an unrecognized symbol. =]] – Hello Everyone Jun 16 '18 at 08:24

unusual C++ constructor

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