Defining array elements using another array's elements

Question

I'm developing a webserver using C++ and I want a string array to contain the HTML code of my HTML elements.

In the definition of that array, I want to supplement hard-coded characters with strings that are defined in other arrays.

For example, my webpages[] array would contain the HTML for each webpage and be defined as:

string webpages[NUM_WEBPAGES] =
{
  ...
  "<p>Please <a href=\"" + urls[PAGE_LOGIN] + "\">login here</a></p>",
  ...
};

However, the HTML that gets sent to the client is:

<p>Please <a href="">login here</a></p>

As you can see, the url from urls[PAGE_LOGIN] was not populated into the HTML.

I have confirmed via code inspection and gdb that urls[PAGE_LOGIN] has the value /login.

(1) Why is this not working?

(2) Is this possible?

(3) If no, any recommendations?

Thank you!

EDIT: Minimal reproducible code example... because I don't know how to stackoverflow.

Also my C++ is bad.

webpages.h:
enum webpage
{
  PAGE_LOGIN,
  NUM_WEBPAGES
};

extern string webpages[NUM_WEBPAGES];

webpages.cpp:
string webpages =
{
  "<p>Please <a href=\"" + urls[PAGE_LOGIN] + "\">login here</a></p>",
};

urls.h:
extern string urls[NUM_WEBPAGES];

urls.cpp:
string urls[NUM_WEBPAGES] =
{
  "/login"
};