Thread: structure dynamic memory allocation?

I have an assignment that's basis is about dynamic memory allocation. I'm given two files. One is a file with the list of months from January-December. I have to allocate space to store all of these. I did that.

The second file has a bunch of dates such as January 17, 2004. I have to store/update a count for each month and year it is in. I wanted to go about this by doing using structures. I read linked lists would be good for this but we don't learn that until next week. Anyways one of the requirements is...

"The memory for storing the counts should by dynamicallyallocated"
So if I do use structures I have to dynamically allocate the memory.

Here's what I have so far. I commented out the struct dates because it wasn't working. But that's to try to help show along the lines of what I'm thinking if this makes sense.

Thanks for any help.

Code:

struct dates
{
       char months[20];
       int years;
};

int main(void)
{
    FILE *fp;
    char buffer[50];
    char **month_and_year = NULL;
    char **list_of_months = NULL;
    int counter1 = 0;
    int counter2 = 0;
    int line_len;
    char *month;
    char *year;
    char *del = ",";
   
    //Opens the first file and stores the months individually in list_of_months 
    if ( (fp = fopen("months.txt", "r" )) == NULL )
    {
    printf("Couldn't open file\n");
    exit(1); 
    }

    while(fgets(buffer, sizeof(buffer), fp))
    {
        list_of_months = realloc(list_of_months, (counter1+1) *sizeof(char*) );
        line_len = strlen(buffer);
        list_of_months[counter1] = calloc(line_len+1, sizeof(char));
        strcpy(list_of_months[counter1],buffer);
        counter1++;         
    }   
fclose( fp );
       
   //Opens the second file and stores the month in month and year in year.                

    if ( (fp = fopen("dates.csv", "r" )) == NULL )
    {
    printf("Couldn't open file\n");
    exit(1); 
    }

    while(fgets(buffer, sizeof(buffer), fp))
    {
        month_and_year = realloc(month_and_year, (counter2+1) *sizeof(char*) );
        line_len = strlen(buffer);
        month_and_year[counter2] = calloc(line_len+1, sizeof(char));
        strcpy(month_and_year[counter2],buffer);
        month = strtok (month_and_year[counter2], del);
        year = strtok (NULL, del);
        //struct dates *array = realloc( array, (counter2+1)*sizeof(char*));
        counter2++;         
    }      
fclose( fp );                                
free(list_of_months);
free(month_and_year); 

 getchar();
 return 0;
}

"Assignment: Write a program that reads a file of dates and counts the number of dates per month
per year. The process you will use is as follows:
• read the file of month names (see below); they should be stored in dynamically allocated
memory (e.g., array of structures, array of pointers to char, etc.)
• read the dates file once. As you read the dates file, update the count for the appropriate month
in the appropriate year. The memory for storing the counts should by dynamically
allocated.
• print the overall results as a table"

There's the main rules of the assignment. So you actually make a good point lol. I didn't even see that. But it's a requirement to read the months and store them. Which I did correctly I think.

And I understand what you wrote but what exactly would the syntax look like?


is it anything similar to

Code:

struct dates *array = realloc( array, (counter2+1)*sizeof(char*))

? I'm understand the how structures work pretty well now I believe. But I don't understand how to allocate memory for structures as I go.

Ok, yea I just sent my instructor an email asking about it. Reread the assignment and don't see any more clarification. The best I can think of is that he gave us the months so that I don't have to sort duplicate months since that's not the point of this assignment. I shall see when he emails me back. Thanks again