在C中的struct的elemnt上使用malloc

Question

I have this struct:

typedef struct
{
    char name[3];
    int month_num;
    int day_num;
    int day_size; // amount of days that are field in with tasks.
    char *task[40];
}

month; // each month contains a name, its num in the calendar and days.

and I need to assign memory allocation for it. I was able to assign the memory for the struct itself:

mon = (month*)malloc(12 * sizeof(month));

But I am having trouble to do it the same for the char *task[40].

I tried a lot of possibilities, but non of them worked...

char temptask[40];
mon->task=malloc(strlen(temptask)+1);

Answer 1

for(i=0;i<40;i++)
{ 
  /* Allocating memory to each pointers and later you write to this location */
  mon->task[i] = malloc(size);/* If you have a initialized string then size = strlen(tempTask) + 1 */
}

What you have is array of pointers and just access them and allocate memory to each of the pointers individually as shown above.

Answer 2

char *task[40]; is an array of 40 pointers. You probably want a single array of 40 characters, in which case no need to malloc it separately, or else a single pointer in which case you can malloc(40) . You can't call strlen() on an uninitialized C string, that's undefined behavior (buffer overrun).

Answer 3

I think, what you need is

char *task;

and then allocate memory as

mon[j].task=malloc(sizeof(temptask));

Next, as you've allocated memory to mon as

 mon = malloc(12 * sizeof(month));

the access should be made as

 mon[j].task  // j being the index, running from 0 to 11

Otherwise, if you really have a char *task[40]; , that means, an array of 40 char * s, then you have to allocate memory for each of them , one by one.

int p = strlen(temptask);
for(i=0;i<40;i++)
{
      mon[j].task[i] = malloc(p+1);
}