Can someone explain how to append an element to an array in C programming?

Question

If I want to append a number to an array initialized to int, how can I do that?

int arr[10] = {0, 5, 3, 64};
arr[] += 5; //Is this it?, it's not working for me...

I want {0,5, 3, 64, 5} in the end.

I'm used to Python, and in Python there is a function called list.append that appends an element to the list automatically for you. Does such function exist in C?

Answer 1

int arr[10] = {0, 5, 3, 64};
arr[4] = 5;

EDIT: So I was asked to explain what's happening when you do:

int arr[10] = {0, 5, 3, 64};

you create an array with 10 elements and you allocate values for the first 4 elements of the array.

Also keep in mind that arr starts at index arr[0] and ends at index arr[9] - 10 elements

arr[0] has value 0;
arr[1] has value 5;
arr[2] has value 3;
arr[3] has value 64;

after that the array contains garbage values / zeroes because you didn't allocated any other values

But you could still allocate 6 more values so when you do

arr[4] = 5;

you allocate the value 5 to the fifth element of the array.

You could do this until you allocate values for the last index of the arr that is arr[9];

Sorry if my explanation is choppy, but I have never been good at explaining things.

Answer 2

There are only two ways to put a value into an array, and one is just syntactic sugar for the other:

a[i] = v;
*(a+i) = v;

Thus, to put something as the element at index 4, you don't have any choice but arr[4] = 5.

Answer 3

You can have a counter (freePosition), which will track the next free place in an array of size n.