C Programming
 
Forums: » Register « |  User CP |  Games |  Calendar |  Members |  FAQs |  Sitemap |  Support | 
User Name:
Password:
Remember me

The Shed is going Social! Join us on FaceBook and Twitter and chime in on the conversation.

Go Back   Dev Shed Forums > Programming Languages > C Programming
Reload this Page

What's wrong with the syntax?


Reply
Add This Thread To:
  Del.icio.us   Digg   Google   Spurl   Blink   Furl   Simpy   Y! MyWeb 
« Previous Thread | Next Thread »  
Thread Tools Search this Thread Rate Thread Display Modes
 
Unread Dev Shed Forums Sponsor:
  #1  
Old February 4th, 2013, 04:06 PM
so.very.tired so.very.tired is offline
Contributing User
Dev Shed Newbie (0 - 499 posts)
  
Join Date: Nov 2012
Posts: 112 so.very.tired User rank is Just a Lowly Private (1 - 20 Reputation Level) 
Time spent in forums: 1 Day 4 h 12 m 48 sec
Reputation Power: 1
What's wrong with the syntax?
Hi guys.

i'm trying to define the following:

Code:
typedef struct
{
	professor* current;
	list* next;
}list;


but i'm getting a compilation error: "unknown type name 'list'".
how come?

how else can i define a nested struct of the same type?

thanks in advanced!
Reply With Quote
  #2  
Old February 4th, 2013, 04:21 PM
dwise1_aol's Avatar
dwise1_aol dwise1_aol is offline
Contributing User
Dev Shed God 2nd Plane (6000 - 6499 posts)
  
Join Date: Jan 2003
Location: USA
Posts: 6,139 dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level)dwise1_aol User rank is General 15th Grade (Above 100000 Reputation Level) 
Time spent in forums: 2 Months 2 Weeks 3 Days 23 h 8 m 12 sec
Reputation Power: 1974
There may be other ways. I actually had to look this one up, since my schooling in linked lists was in my pre-C days, and since C++'s approach to a similar problem is slightly different syntactically.

Code:
typedef struct _list
{
	professor* current;
	struct _list* next;
}list;

For the field, next, the compiler has to already know about list, but it doesn't yet. However, it does know about struct _list. And since in subsequent code and declarations list will already be known to be struct _list, next should be compatible with pointers declared as list* .

Hopefully there are better solutions, but I just can't think of any.
Last edited by dwise1_aol : February 4th, 2013 at 04:25 PM.
Reply With Quote
  #3  
Old February 4th, 2013, 04:31 PM
so.very.tired so.very.tired is offline
Contributing User
Dev Shed Newbie (0 - 499 posts)
  
Join Date: Nov 2012
Posts: 112 so.very.tired User rank is Just a Lowly Private (1 - 20 Reputation Level) 
Time spent in forums: 1 Day 4 h 12 m 48 sec
Reputation Power: 1
yup. thanks man.
now it compiles without any errors.

only now, Eclipse warns me every time i try to assign from "struct list" type to "list" type and vise versa, since it sees them as different types ("assignment from incompatible pointer type").
nothing i can't live with, though...
Reply With Quote
  #4  
Old February 4th, 2013, 05:12 PM
b49P23TIvg's Avatar
b49P23TIvg b49P23TIvg is offline
Contributing User
Dev Shed Loyal (3000 - 3499 posts)
  
Join Date: Aug 2011
Posts: 3,383 b49P23TIvg User rank is Major (30000 - 40000 Reputation Level)b49P23TIvg User rank is Major (30000 - 40000 Reputation Level)b49P23TIvg User rank is Major (30000 - 40000 Reputation Level)b49P23TIvg User rank is Major (30000 - 40000 Reputation Level)b49P23TIvg User rank is Major (30000 - 40000 Reputation Level)b49P23TIvg User rank is Major (30000 - 40000 Reputation Level)b49P23TIvg User rank is Major (30000 - 40000 Reputation Level)b49P23TIvg User rank is Major (30000 - 40000 Reputation Level)b49P23TIvg User rank is Major (30000 - 40000 Reputation Level)b49P23TIvg User rank is Major (30000 - 40000 Reputation Level) 
Time spent in forums: 1 Month 2 Weeks 3 Days 13 h 44 m 42 sec
Reputation Power: 383
A preprocessor alternative (much despised by some) I use:
Code:
#define NODE struct node_structure
NODE {
  void*data;
  NODE*next;
};

NODE*stack;
__________________
[code]Code tags[/code] are essential for python code!
Reply With Quote
  #5  
Old February 4th, 2013, 05:33 PM
Scorpions4ever's Avatar
Scorpions4ever Scorpions4ever is offline
Banned ;)
Dev Shed God 9th Plane (9000 - 9499 posts)
  
Join Date: Nov 2001
Location: Woodland Hills, Los Angeles County, California, USA
Posts: 9,389 Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level)Scorpions4ever User rank is General 46th Grade (Above 100000 Reputation Level) 
Time spent in forums: 1 Month 4 Weeks 1 Day 22 h 17 m 29 sec
Reputation Power: 4080
Quote:
Originally Posted by so.very.tired
yup. thanks man.
now it compiles without any errors.

only now, Eclipse warns me every time i try to assign from "struct list" type to "list" type and vise versa, since it sees them as different types ("assignment from incompatible pointer type").
nothing i can't live with, though...

Did you notice that struct _list has a leading underscore in front of it, whereas the typedef doesn't. Just declare all your variables to be of type list instead of struct _list and you should have no warnings.
__________________
Up the Irons
What Would Jimi Do? Smash amps. Burn guitar. Take the groupies home.
"Death Before Dishonour, my Friends!!" - Bruce D ickinson, Iron Maiden Aug 20, 2005 @ OzzFest
Down with Sharon Osbourne
Reply With Quote
  #6  
Old February 5th, 2013, 05:11 AM
clifford's Avatar
clifford clifford is offline
Contributing User
Dev Shed Demi-God (4500 - 4999 posts)
  
Join Date: Aug 2003
Location: UK
Posts: 4,808 clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level)clifford User rank is General 12nd Grade (Above 100000 Reputation Level) 
Time spent in forums: 1 Month 2 Days 17 h 42 m 37 sec
Reputation Power: 1800
An alternative is to use C++ compilation where the typedef nonsense is unnecessary:

In C++:
Code:
struct list
{
	professor* current;
	list* next;
} ;

Defines a type list that does not require the struct keyword to be used everywhere it is referenced.

That said the C++ standard library includes a list container class that would probably make this struct redundant in any case.
Reply With Quote
Reply

Viewing: Dev Shed Forums > Programming Languages > C Programming > What's wrong with the syntax?

« Previous Thread | Next Thread »

Developer Shed Advertisers and Affiliates



Thread Tools  Search this Thread 
Search this Thread:

Advanced Search
Display Modes  Rate This Thread 
Linear Mode Linear Mode
Rate This Thread:


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
View Your Warnings | New Posts | Latest News | Latest Threads | Shoutbox
Forum Jump

Forums: » Register « |  User CP |  Games |  Calendar |  Members |  FAQs |  Sitemap |  Support | 
  
 


Powered by: vBulletin Version 3.0.5
Copyright ©2000 - 2013, Jelsoft Enterprises Ltd.

© 2003-2013 by Developer Shed. All rights reserved. DS Cluster - Follow our Sitemap