What does this mean
[insert]My thinking goes that elementT is a structure which has these two elements (data and a pointer link). But what is this term element after the braces signify and for what purpose it is used?Code:typedef struct elementT { int data; struct elementT *link; } element;
No, struct elementT is the name of the structure type, and element is an alias of the structure type.Originally Posted by roaan
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And elementT itself is an identifier which lives in the "structure tag" namespace. This identifier doesn't specify a type, but when prefixed with struct it does. Welcome to C land
Code://try //{ if (a) do { f( b); } while(1); else do { f(!b); } while(1); //}
Okay so that implies i can make declarations like
element S1, S2 ;
S1 -> data = some value
S1 -> next = some address // all this is ok
but this is
elementT S1, S2;
S1 ->data = some value
S1 -> next = some address // this is wrong
Correct. But you COULD do:
The purpose of the typedef is to create a more convenient alias for "struct elementT" instead of saying "struct" everywhere.Code:struct elementT S1, S2; S1 ->data = some value S1 -> next = some address // this is wrong
Code://try //{ if (a) do { f( b); } while(1); else do { f(!b); } while(1); //}
Also the only way a structure can make use of itself within its defined structure is with the use of pointer. This is an alias to how linked lists are created and thus what we call an ADT (abstract data type).
Using S1->next is not correct as you have not defined what next is. In your example you will simply call
Code:element *next; S1->link = next /*Or some other pointer to an elementT structure */
Oh i meant that
S1 ->link = some address
Just one more stuff till now i have only been using for linked lists declarations of type
[insert]and used it likeCode:struct node { int data; struct node *link; };
struct node *start;
What is the advantage of typedef over this declaration.
There isn't much of an advantage. It just saves you from a little extra typing.What is the advantage of typedef over this declaration.
Yeah, using typedefs for structs is a more intuitive measure to help define, what your struct is and how it is to be used. Simply stated - it saves in coding a bit as you do not have to use the keyword struct with every declaration call.
You'll see what advantage this brings. Many times 7 letters ("struct" plus space) and easier maintainability. (what if your user-defined "struct IMAGE" suddenly becomes an int for some obscure reason? Or your opaque "file_t" now uses stdio.h instead of file-descriptors?)
