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: Beginner
Aug 28, 1998

WEBINAR:

On-Demand

Application Security Testing: An Integral Part of DevOps


Standard vs. User Defined Conversions in Overloaded Function Call

A non-explicit constructor taking a single argument is also a conversion operator, which casts its argument to an object of the constructor's class. When the compiler has to resolve an overloaded function call, it takes into consideration this user-defined cast:
 
class Numeric { 
float f;
public:
Numeric(float ff): f(ff) {}//constructor is also a float-to-Numeric conversion operator
};
void f(Numeric&); //function prototype
Numeric num(0.05); //object
f(5f);  //calls void f(Numeric&). Numeric's constructor converts argument to a Numeric object 
However, suppose we add a new overloaded version of f:
 
void f (double);
Now the same function call will resolve differently:
 
f(5f); //calls f(double); standard conversions have higher precedence than user-defined ones
This is because float variables are converted to double automatically in order to match an overloaded function signature. This type promotion is defined by the C++ standard. On the other hand, the conversion of float to Numeric is user-defined. User defined conversions rank lower than standard ones when the compiler has to decide which overloaded version is to be called.
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