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arraysmemorydynamicstructmalloc
TonyW
TonyW

Reputation: 18875

how to allocate memory to a struct that contains a dynamic array? (C)

I am not quite clear on how to allocate memory to a struct pointer that contains a dynamic array field. for example, I have the following struct:

typedef struct log_file {
    char *name;
    int updatesize;
    int numupdates;
    int *users;  /* dynamic array of integers */
} log_data;

When I created a pointer of log_data using: log_data *log_ptr = malloc(sizeof(log_data));

How do I allocate enough memory for the dynamic array users in the struct?

Upvotes: 0

Views: 97

Answers (1)

barak manos
barak manos

Reputation: 30136

How about:

log_ptr->users = malloc(sizeof(int)*numOfUsers);

Or if you want to keep it independent of the type of *users:

log_ptr->users = malloc(sizeof(*log_ptr->users)*numOfUsers);

Upvotes: 1

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