Question

I wrote this function that uses a binary search to look for a specific value in an array of structs. Why doesn’t it compile?

I’m getting this error:

prog.c:224: error: subscripted value is neither array nor pointer
prog.c:226: error: subscripted value is neither array nor pointer

This is the function:

int FieldSearch(Field *pArr, int size, int val)
{
    int low=0,high=size-1, middle;
    while (low <= high)
    {
        middle = (low + high)/2;
        if (val == pArr->Id[middle])
            return middle;
        else if (val < pArr->Id[middle])
            high = middle -1;
        else
            low = middle +1;
    }
    return NOT_FOUND;
}

This is the field struct:

typedef struct field
{
        char Id;
        Coordinates location;
        int area;
        int price;
} Field;

Maybe the prototype is wrong…

Answer 1

If you want to search the “array” pArr, you need to put the brackets directly behind the identitifier. This should work:

pArr[middle].Id