im pretty new to game development. Before i start making some game, im trying to figure out how i will manage thing. One of the first thing im not sure about, is how to manage entity (enemy, player, projectile...)

Language i could use, since these are language i know or im learning: C, C++, JAVA, C#

One of the idea i got is to use an array for projectile, one for enemy, each time i have a new entity, i grow my array. Here is the problem: If player/enemy is firing, new entity, projectil array is growing. Suppose its projectil #2053, when it hit something, i free it, then in my loop to check which projectil are to do something, like getting closer to there target, i check if every # of my array to see if its null, if not, check is trajectory. But the problem is that the array will grow each time a new projectil is fired, and i will get a memory problem at the end, how should i manage entity? (sorry if its unclear, its even unclear to me on how i will do thing). Can someone explain me how to manage entity, or point me to any good article about this?

I need an awnser that cover both, object oriented and standard, since i mainly do thing in C.

Here is what i understand on how to use entity:

Before I start making a game, I'm trying to figure out how I will manage things. One of the first things I'm not sure about is how to manage entities (enemy, player, projectile...)

I'm going to be using either C, C++, Java, or C#

One of the ideas I have is to use one array for projectiles and one for enemies. Each time I have a new entity, I grow my array. Here is the problem: If player/enemy is firing, that creates a new entity which means the projectile array is growing. 

Suppose its projectile #2053, when it hit something, I free it, then in my loop to check which projectiles are to do something, like getting closer to there target, I check if every # of my array to see if its null, if not, check is trajectory. But the problem is that the array will grow each time a new projectile is fired, and I will get a memory problem at the end.

So how should I manage my entities?

I need an awnser that covers both object oriented and procedural, since I mainly do things in C.