Some missed file for gdbm on ubuntu

I want to write a program based on GBDM on ubuntu. I Installed ubuntu, gcc and make.

After installing (Os, gcc, make), I search for any files related to gdbm (*.a, *.so, *.h), and I saw only the following files:

/usr/share/doc/libgdbm-compat4/usr/share/doc/libgdbm6/usr/lib/x86_64-linux-gnu/libgdbm_compat.so.4/usr/lib/x86_64-linux-gnu/libgdbm.so.6/usr/lib/x86_64-linux-gnu/libgdbm_compat.so.4.0.0/usr/lib/x86_64-linux-gnu/libgdbm.so.6.0.0

I manually, created soft link for

/usr/lib/x86_64-linux-gnu/libgdbm.so

as

ln -s /usr/lib/x86_64-linux-gnu/libgdbm.so.6 /usr/lib/x86_64-linux-gnu/libgdbm.so

But I could not find any gdbm.h(or related .h), so I downloaded sample gdbm.h (however I could get it from installing gdbm-dev or etc).

My questions is:

1- Is it normal that there exists library file (libgdbm.so.6) but there doesn't exists related header file?

2- What is the best (or popular) way for solving this problem!