array of structure pointers

[jamesbon]

I am trying to make a graph this program is just in initial phases where I
declared an array of structure pointers which holds address of vertices
*vertices[20] is an array which whose elements are all addresses of type struct node * which will contain the address of node of graphs.


#include<stdio.h>
#include<stdlib.h>
struct node {
int data;
struct node *links[10];
};
struct node *create_node(int);
void create_vertices(struct node **);
int main()
{
struct node *vertices[20];
int d, i, choice;
*vertices[0]=(struct node *)malloc(sizeof(struct node)*20);
create_vertices (&vertices);
}

struct node *create_node(int data)
{
int i;
struct node *temp = (struct node *)malloc(sizeof(struct node));
temp->data = data;
for (i = 0; i < 10; i++)
temp->links[i] = NULL;
return temp;
}

void create_vertices (struct node **v)
{
int i,choice;
i=0;
printf("enter choice\n");
scanf("%d", &choice);
while (choice == 1) {
printf("enter data\n");
scanf("%d", &d);
vertices[i] = create_node(d);
i++;
printf("enter choice\n");
scanf("%d", &choice);
}
}



Compiling the above code gives me following errors



bfs.c: In function ‘main’:
bfs.c:13:21: error: incompatible types when assigning to type ‘struct node’ from type ‘struct node *’
bfs.c:14:9: warning: passing argument 1 of ‘create_vertices’ from incompatible pointer type [enabled by default]
bfs.c:8:6: note: expected ‘struct node **’ but argument is of type ‘struct node * (*)[20]’
bfs.c: In function ‘create_vertices’:
bfs.c:35:16: error: ‘d’ undeclared (first use in this function)
bfs.c:35:16: note: each undeclared identifier is reported only once for each function it appears in
bfs.c:36:3: error: ‘vertices’ undeclared (first use in this function)



the program says an error in following line


struct node *vertices[20];
*vertices[0]=(struct node *)malloc(sizeof(struct node)*20);

what is the harm in this kind of declaration.
I declare an array of pointers of type struct node * should I not give memory also to them.

I have a confusion here how will vertices[1] be stored because if I give all the memory to vertices[0] what I am trying to do is create an array vertices[0],vertices[1],vertices[2],vertices[3] and so on I am trying to use malloc for the same.

[Bachstelze]

#include <stdio.h>
#include <stdlib.h>

struct node {
int data;
struct node *links[10];
};

struct node *create_node(int);
void create_vertices(struct node **);

int main(void)
{
struct node *vertices[20];
create_vertices (vertices);
}

struct node *create_node(int data)
{
int i;
struct node *temp = malloc(sizeof(struct node));
temp->data = data;
for (i = 0; i < 10; i++)
temp->links[i] = NULL;
return temp;
}

void create_vertices (struct node **v)
{
int i, d, choice;
i=0;
printf("enter choice\n");
scanf("%d", &choice);
while (choice == 1) {
printf("enter data\n");
scanf("%d", &d);
v[i] = create_node(d);
i++;
printf("enter choice\n");
scanf("%d", &choice);
}
}