What is the best way to progressively fill an array in C? -

suppose have array, defined as

int arr[10]; 

i want progressively fill array (assuming not run out of memory allocated array), according loop of form

for(int = 0; < some_number; i++)   if(some_condition)     add_element_to_arr 

what best way this? 2 methods can think of 1) using auxiliary variable remember number of stored values, or 2) using pointer same thing.

what preferred/standard/conventional way this?

also, having kind of operations multiple arrays, remember how many values have been added each array 1 has use auxiliary variable each array. preferred way deal this?

you use pos variable this:

for(int = 0, pos = 0; < some_number && pos < 10; i++)   if(some_condition)     arr[pos++] = i; 

no need use pointer in case.

update:

with multiple arrays (different sizes), create struct pointer array , current position, way both values stay together:

struct arr_data {     int *arr;     int current_pos; } 

and add size maybe:

struct arr_data {     int *arr;     int size;         // or unsigned int or size_t     int current_pos;  // or unsigned int or size_t } 

you create array of structs, depending on implementation.