Re: [Boost-Users] testing if shared_ptr has been assigned

From: dick.bridges_at_[hidden]
Date: 2002-12-12 12:19:27

I should point out that I went 'back' to get() because I got tired of
explaining the 'correct' way [ie, if( b ) ] Darin Adler provided in his
answer.

|---------+---------------------------------------------------->
|         |           Dick                                     |
|         |           Bridges/CSE/IRV/CONTRACTOR/TOSHIBA-TAIS_at_T|
|         |           OSHIBA-TAIS                              |
|         |                                                    |
|         |           12/12/2002 08:07 AM                      |
|         |           Please respond to Boost-Users            |
|         |                                                    |
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  >----------------------------------------------------------------------------------------------|
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  |        To:      Boost-Users_at_[hidden]                                                  |
  |        cc:                                                                                   |
  |        Subject: Re: [Boost-Users] testing if shared_ptr has been assigned                    |
  >----------------------------------------------------------------------------------------------|

>From the docs:
<snippet>
get

T * get() const; // never throws
Returns: the stored pointer.

Throws: nothing.
</snippet>

Therefore you can use
      if( b.get() )
or
      if( b.get() == NULL )

                      "TEA Hartmann,

                      Steven"                  To:
boost-users_at_[hidden]

                      <SHartmann_at_aus.t         cc:

                      elusa.com>               Subject: [Boost-Users]
testing if shared_ptr has been assigned

                      12/11/2002 11:01

                      AM

                      Please respond

                      to Boost-Users

I need some help in testing for the condition of whether a shared_ptr has
been assigned.  In the following example, the "if( b != NULL ) does not
work. How would I do this test?

typedef boost::shared_ptr<int> IPtr;

int i( 0 );
IPtr a( i );
IPtr b;

if( some condition )
             b = a;

if( b != NULL ) { // How should this really be coded?
}

Best Regards,

Steve

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