How could I initialize an array of struct to null?

Question

    typedef struct 
    {
        char*title;
        int year;
        int length; //in minutes
    } record;

    record list[1024];
    int j;
    for(j=0;j<1024;++j)
        list[j]=NULL;

I am trying to initialize an array of struct and let each element point to null initially. gcc gives me an error "incompatible types when assigning to type 'record' from type 'void*". How could I solve it? The purpose of doing this is when I access an element I am able to see if it has data or just empty.

Answer 1

You can initialize your array at declaration time this way:

record list[1024] = {{0}};

Answer 2

list[1024]; is array of object of your struct, which you access like

list[j].title;
list[j].year;
list[j].length; 

What you are doing is:

list[j]=NULL

list[j] is of type record, NULL is void*. I guess this is not what you have in mind.

Either initialize individual elements in the struct by accessing them individually or use memset as suggested by others.

Answer 3

If you want to do it one at a time in a for loop, it would look like this

for(j=0;j<1024;++j)
    list[j]=(record){0,0,0};

I would suggest using memset(list,0,1024*sizeof(record))

or bzero(list, 1024*sizeof(record))

If you want to do it with pointers, then you could declare your array like this:

record * list[1024];

Then you could set each one to NULL like you are and malloc each one when you're ready for it.

Answer 4

Your array is not an array of pointers to records, it is an array of record values. You cannot set the elements of the array to NULL because they are not pointers. This is not java...