• Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Jeanne Boyarsky
  • Ron McLeod
  • Paul Clapham
  • Liutauras Vilda
Sheriffs:
  • paul wheaton
  • Rob Spoor
  • Devaka Cooray
Saloon Keepers:
  • Stephan van Hulst
  • Tim Holloway
  • Carey Brown
  • Frits Walraven
  • Tim Moores
Bartenders:
  • Mikalai Zaikin

+= and ++

 
Greenhorn
Posts: 10
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
How come the following work?
byte a=2,b;
b=a+1; // doesn't work - needs a cast
b=a++; // it works, why? - shouldn't it need a cast?
long L=1;
int i=0;
i=i+L; // not okay - needs a cast
i+=L; // okay, why? - shouldn't it need a cast also?

 
Greenhorn
Posts: 11
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
when +=,++ is used cast is automatic
 
Greenhorn
Posts: 10
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
The statement b = a++ works not because there is an automatic cast, but because a is incremented as a byte and assigned to b, which is also a byte.
In the statement i = i + L the cast is automatic, and it is to a long type. A long won't fit into the int on the left side of the assignment operator, so you have to do an explicit cast to force the issue.
The statement i += L works because of the compound operator; i becomes a long because the largest data type in the expression is a long. I hope this hslps.
[This message has been edited by Barbara Dyer-Bennet (edited September 15, 2000).]
 
Ranch Hand
Posts: 18944
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
I tried the same with double i.e saying i+=d(where double d=1.0)and when i displayed it on console I'm getting int value and not as double as pointed out...(that the compound statement will be casted to largest data type in the expression) .
 
Anonymous
Ranch Hand
Posts: 18944
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
hi,
i tried with bytes byte b1=1,int i=1;and when i perform b1+=1;
it is giving explicit casting is required...i could not get to
final conclusion on this..is there any version problem..
 
Ranch Hand
Posts: 41
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Hi Satish,
I agree with barbara. it is that when the += operator is used its equivalent to the operator and cast before the right side. whereas its not the case with + operator.

Cheers
Satish
 
jayanthi
Greenhorn
Posts: 11
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
with +=, ++ cast is automatic
i think so...
jayanthi
 
Anonymous
Ranch Hand
Posts: 18944
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
OOPs!! I posted it wrongly, b1+=1 is working fine.
Sorry for the mistake..
 
Consider Paul's rocket mass heater.
reply
    Bookmark Topic Watch Topic
  • New Topic