c - How do I traverse a memory block in a struct with pointers? -

goal: traverse vertices memory block in heap struct.

errors: expected unqualified-id before ‘(’ token when trying access vertices. also, ‘vertices’ not declared in scope.

header:

typedef struct heap *priorityqueue_t; typedef struct heapitem *priorityitem_t;  priorityqueue_t init(int max_capacity, int source_vertex); 

implementation:

#include "heap.h" #include <stdlib.h> #include <limits.h>  struct heap {   int size;   priorityitem_t vertices; };  struct heapitem {   int id;   int distance; };  priorityqueue_t init(int max_capacity, int source_vertex) {   priorityqueue_t q;    q = (priorityqueue_t)malloc(sizeof(priorityqueue_t));   q->vertices = (priorityitem_t)malloc(sizeof(priorityitem_t)*max_capacity);    q->size = max_capacity;    int i;   for(i = 0; < q->size; i++)   {     q->(vertices + i)->id = i; //errors on line.     q->(vertices + i)->distance = int_max;   }   q->(vertices + source_vertex)->distance = 0;    return q; } 

you've placed parens in wrong place. try this:

    (q->vertices + i)->id = i; //errors on line.     (q->vertices + i)->distance = int_max;   }   (q->vertices + source_vertex)->distance = 0;