dev-cpp-users

[Dev-C++] In constructor parameter list x = null

[Daniel G. <sp...@ho...>]

Can someone explain this to me? It's in a header file for a class 
declaration, for the only constructor of the class.

CPenWidthsDlg(CWnd* pParent = NULL);

It's derived from CDialog so I assume that's got something to do with it. I 
am just confused why the parameter is assigned a NULL value. If I pass in a 
pointer will it just get assigned to NULL? then what's the point? To save me 
from having to assign it to NULL in the constructor body or something?





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RE: [Dev-C++] In constructor parameter list x = null

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: dev...@li... 
> [mailto:dev...@li...] On Behalf 
> Of Daniel Glenfield
> Sent: Monday, March 31, 2003 4:00 PM
> To: dev...@li...
> Subject: [Dev-C++] In constructor parameter list x = null
> 
> 
> Can someone explain this to me? It's in a header file for a class 
> declaration, for the only constructor of the class.
> 
> CPenWidthsDlg(CWnd* pParent = NULL);
> 
> It's derived from CDialog so I assume that's got something to 
> do with it. I 
> am just confused why the parameter is assigned a NULL value. 
> If I pass in a 
> pointer will it just get assigned to NULL? then what's the 
> point? To save me 
> from having to assign it to NULL in the constructor body or something?


If you do not pass any value NULL is passed. In the invocation style:

// ...

CPenWidthsDlg();

// ...



Ioannis Vranos
 
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