Question

Task:

I have an array of records in filtered_records, with the number of filtered records in
num_filtered_records. I want to duplicate this information in binfo->filtered_records
and binfo->num_filtered_records since filtered_records are free’d later in my code.

Definitions:

char** filtered_records;
size_t num_filtered_records;  

Snippet:

binfo->filtered_records = malloc(num_filtered_records*sizeof(char*));

memcpy(binfo->filtered_records, 
       filtered_records,
       num_filtered_records * sizeof(char*));

Issue:

When I print binfo->filtered_records, I see all the records, but some of the records have
been replaced by values which are just incorrect. I am not sure what I am missing.

Answer 1

What you are doing doesn’t duplicate the actual data, it just copies pointers. Instead of that memcpy, do a for:

for (i = 0; i < num_filtered_records; i++)
    binfo->filtered_records[i] = strdup(filtered_records[i]);

If you don’t have strdup, use malloc(strlen(filtered_records[i]) + 1) and then strcpy.