Question

I read to get the length of array in C++, you do this:

int arr[17];
int arrSize = sizeof(arr) / sizeof(int);

I tried to do the same for a string:
where I have

string * arr;
arr = new (nothrow) string [213561];

And then I do

arr[k] = "stuff";

where I loop through each index and put “stuff” in it.

Now I want the size of the array which should be 213561, what’s the correct way to do it and why is it so complex in C++?

Answer 1

The correct way of doing this in C++ is to use a vector. That way you can either specify a size up-front, or resize it as you go.

Specifying size up-front:

using namespace std;
vector<string> arr(213561);

for (vector<string>::iterator p = arr.begin(); p != arr.end(); ++p)
{
  *p = "abc";
}

Expanding the vector as you go:

using namespace std;
vector<string> arr;  // <-- note, default constructor

for (int i = 0; i < 213561; ++i)
{
  // add elements to the end of the array, automatically reallocating memory if necessary
  arr.push_back("abc");
}

Either way, the size of the array is found with:

size_t elements = arr.size();  // = 213561