Dynamic memory in a struct - struct

Question

So, my struct is like this:
struct player{
char name[20];
int time;
}s[50];
I don't know how many players i am going to add to the struct, and i also have to use dynamic memory for this. So how can i allocate and reallocate more space when i add a player to my struct?
I am inexperienced programmer, but i have been googling for this for a long time and i also don't perfectly understand structs.
This site doesn't accept my question so let's put some more text to this post

Answer 1

I assume you are programming in C/C++.
Your struct player has static-allocated fields, so, when you use malloc on it, you are asking space for a 20-byte char array a for one integer.
My suggestion is to store in a variable (or #define a symbol) the initial number of structures you can accept. Then, use malloc to allocate a static array that contains these structures.
Also you have to think about a strategy to store new players coming. The simplest one could be have an index variable to store last free position and use it to add over that position.
A short example follows:
#define init_cap 50
struct player {
char name[20];
int time;
};
int main() {
int index;
struct player* players;
players = (struct player*) malloc(init_cap * sizeof(struct player));
for(i = 0; i < init_cap; i++) {
strcpy(players[i].name, "peppe");
players[i].time = i;
}
free(players);
return 0;
}
At this point you should also think about reallocating memory if the number of players you get a runtime exceeds your initial capacity. You can use:
players = (struct player*) realloc(2 * init_cap * sizeof(struct player));
in order to double the initial capacity.
At the end, always remember to free the requested memory.