How do you access an int pointer inside a struct. This is how it seems like
it would work to me, but it doesn't...
struct maze {
int num;
int * roomnum;
};
void setmaze(struct maze * maze) {
maze->num = 1; //this is equivelant to: (*maze).num = 1
maze->(*roomnum) = 5;
}
--
Jason
[ jake1138 AT yahoo DOT com ] 5 9119
"Jason" <ja******@NO.SP AM.yahoo.com> wrote in message
news:bg******** **@terabinaries .xmission.com.. . How do you access an int pointer inside a struct. This is how it seems like it would work to me, but it doesn't...
struct maze { int num; int * roomnum; };
void setmaze(struct maze * maze) { maze->num = 1; //this is equivelant to: (*maze).num = 1 maze->(*roomnum) = 5; }
That last line should be
*maze->roomnum = 5;
or, to make it clearer,
*(maze->roomnum) = 5;
I'm assuming roomnum is pointing somewhere valid.
Regards,
Russell Hanneken rh*******@pobox .com
Jason wrote: How do you access an int pointer inside a struct. This is how it seems like it would work to me, but it doesn't...
struct maze { int num; int * roomnum; };
void setmaze(struct maze * maze) { maze->num = 1; //this is equivelant to: (*maze).num = 1 maze->(*roomnum) = 5; }
As far as anyone can see, maze is the tag of a structure declaration. We
can see no structure object defined. 'struct maze *maze' is therefore
nonsense. How about this...
typedef struct maize {
int num;
int *roomnum;
} maize; /* Corny, right? */
Now maize is a user defined type for a structure. We can define a
structure of this type with something like this..
maize maze;
Now maze is a structure and maze.num is (int) and maze.roomnum is (int
*).
--
Joe Wright mailto:jo****** **@earthlink.ne t
"Everything should be made as simple as possible, but not simpler."
--- Albert Einstein ---
Joe Wright wrote: Jason wrote:
How do you access an int pointer inside a struct. This is how it seems like it would work to me, but it doesn't...
struct maze { int num; int * roomnum; };
void setmaze(struct maze * maze) { maze->num = 1; //this is equivelant to: (*maze).num = 1 maze->(*roomnum) = 5; }
As far as anyone can see, maze is the tag of a structure declaration. We
Right. And `struct maze' is the type of the structure to which the
argument `maze' points. You're solving a problem that doesn't exist.
can see no structure object defined. 'struct maze *maze' is therefore nonsense. How about this...
typedef struct maize { int num; int *roomnum; } maize; /* Corny, right? */
Now maize is a user defined type for a structure. We can define a structure of this type with something like this..
maize maze;
Now maze is a structure and maze.num is (int) and maze.roomnum is (int *).
HTH,
--ag
--
Artie Gold -- Austin, Texas
Jason wrote: How do you access an int pointer inside a struct. This is how it seems like it would work to me, but it doesn't...
typedef struct maze { int num; int *roomnum; } maze;
void setmaze(maze* maze) { maze->num = 1; //this is equivelant to: (*maze).num = 1 *(maze->roomnum) = 5; // error; roomnum is *not* initialized! }
maze* maze_initialize (maze* p, int rooms) { // private
p->num = rooms;
int* roomnum = (int*)malloc((s ize_t)(rooms*si zeof(int)));
for (int j = 1; j < rooms; ++j) {
roomnum[j] = 1 + j;
}
return p;
}
int maze_rooms(cons t maze* p) {
return p->num;
}
maze maze_create(int n) { // default maze [pseudo]constructor
maze m;
maze_initialize (&m, n);
return m;
}
void maze_destroy(co nst maze* p) { // maze [pseudo]destructor
free((void)(((m aze*)p)->roomnum));
}
E. Robert Tisdale wrote:
<snip> void maze_destroy(co nst maze* p) { // maze [pseudo]destructor free((void)(((m aze*)p)->roomnum));
free() takes as its parameter a pointer value previously returned by malloc,
calloc, or realloc.
Your compiler should have warned you about this.
--
Richard Heathfield : bi****@eton.pow ernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
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