Initializing Arrays in C/C++ With Unknown Size [closed]

Question

How can I initialize an array in C such as

void initArr(int size)
{
  ...
}

The C language does not give the option to initialize an array if his size is not an constant value, and if I initialize it generally (int *arr;) so it gives me error of 'arr' is not being initialized.

Similarily, how can I do that when I have an array with dimension bigger than one (matrix, for example)?

Answer 1

The answer that works in C and C++ is dynamic memory allocation

int *arr = (int*)malloc(size*sizeof(int));

In C++ you would prefer to use new instead of malloc, but the principle is the same.

int* arr = new int[size];

Answer 2

The C language does not give the option to initialize an array if his size is not an constant value

In C99 you can use a variable length array and then initialize it by using a loop.

if I initialize it generally (int *arr;) so it gives me error of 'arr' is not being initialized.

This is because a pointer must be initialized (points to a pointee - excluding NULL) before it is being used in program.