Error while freeing an array within a data structure - data-structures

Question

Status bit_flags_set_flag(BIT_FLAGS hBit_flags, int flag_position) {
Bit_Flags* temp = (Bit_Flags*)hBit_flags;
int* nums;
int i;
int old_size;
if (temp->size < flag_position) {
nums = malloc(sizeof(int)*flag_position+1);
if (nums == NULL) {
return FAILURE;
}
for (i = 0; i < temp->size; i++) {
nums[i] = temp->data[i];
}
free(temp->data);
temp->data = nums;
old_size = temp->size;
temp->size = flag_position + 1;
for (i = old_size; i < temp->size; i++) {
temp->data[i] = 0;
}
}
temp->data[flag_position / 32] |= 1 << flag_position % 32;
return SUCCESS;
}
according to the debugger the error is from the free(temp->data) part. however. I only run into the error the second time I go through the function. any ideas what is happening here.
am getting a heap corruption error on visual studio.

Answer 1

I am writing on some assumptions like you are assuming int size is 32 bits and you are trying to set the bit at flag_position in the bitset and you are using 1 int for 1 bit for setting and unsetting bits
Few comments now
temp->data[flag_position / 32] |= 1 << flag_position % 32; now this doesn't make any sense, this line role is to set bit at flag_position, this should be temp->data[flag_position] = 1; instead because if you see your code your are using ints for each bit.
Also this line temp->size = flag_position + 1; is also incorrect , this should be temp->size = flag_position;