dcsimg
Login | Register   
RSS Feed
Download our iPhone app
TODAY'S HEADLINES  |   ARTICLE ARCHIVE  |   FORUMS  |   TIP BANK
Browse DevX
Sign up for e-mail newsletters from DevX

By submitting your information, you agree that devx.com may send you DevX offers via email, phone and text message, as well as email offers about other products and services that DevX believes may be of interest to you. DevX will process your information in accordance with the Quinstreet Privacy Policy.


Tip of the Day
Language: C++
Expertise: Intermediate
Mar 18, 1999

WEBINAR:

On-Demand

Application Security Testing: An Integral Part of DevOps


Declaring Variables Inside an If-Condition

C++ allows you to declare variables just before their use rather than at the top of the enclosing block. Thus, it is legal to declare a variable inside the condition of an if-statement:
 
class Base {/*..*/};
class Derived: public Base {/*..*/};
void func (Base& b)
{
  if ( Derived *pd = dynamic_cast < Derived* > (&b) ) //declaration inside if-condition
  {
    //dynamic_cast was successful; use pd here
    return;
  }//pd goes out of scope at this point 

  //otherwise dynamic_cast failed; variable pd is not in scope
}
The advantage of declaring the pointer pd locally is obvious: it is always initialized with an appropriate value, and it isn't visible to other parts of the program that should not use it.
Danny Kalev
 
Comment and Contribute

 

 

 

 

 


(Maximum characters: 1200). You have 1200 characters left.

 

 

Sitemap
×
We have made updates to our Privacy Policy to reflect the implementation of the General Data Protection Regulation.
Thanks for your registration, follow us on our social networks to keep up-to-date