Why is this showing compilation error?

Question

Help me sort this out?
https://code.sololearn.com/cIPKR7F2LGFM/?ref=app

Answer 1

Seems like sololearn decided to just display "Compilation Error" instead of showing a long chain of errors I saw when I ran it on a different compiler.
The main problem is that showstack returns void (nothing).

Answer 2

showstack() returns void, so you are trying to print a nonexisting value when saying
cout << showstack();

You should call the function on its own, i.e.
cout << "Stack contains:" << endl;
showstack( s );

Answer 3

Your code is perfect I think sololearn doesn't provide stack header file that's why it is giving error.

I run your code on codeblocks it runs perfect.
Your code is perfect just try any other compiler.