THINK C (and later, Symantec C++) featured a class library and
framework for Mac programming called the Think Class Library (TCL),
which was used extensively for Macintosh application development.

Mac GUI has a bunch of versions hosted:
<http://macgui.com/downloads/?cat_id=307>

First DL is a StuffIt 3.6 folder holding the four 800k HFS images.
Second DL is the installed package in an IMG container for emulators.

See Also:
THINK C [3.0.2][1], [4.0][2], [5.0][3], [6.0][4]
Symantec C++ [6.0][5], [7.0][6], [8.6][7]
[Think C From Scratch][8], [Macintosh C Programming by Example][9]

Compatibility
Architecture: 68k

  [1]: http://macintoshgarden.org/apps/thinks-lightspeedc-302
  [2]: http://macintoshgarden.org/apps/think-c-40
  [3]: http://macintoshgarden.org/apps/think-c
  [4]: http://macintoshgarden.org/apps/symantec-think-c-60
  [5]: http://macintoshgarden.org/apps/symantec-c-60
  [6]: http://macintoshgarden.org/apps/symantec-c-70
  [7]: http://macintoshgarden.org/apps/symantec-c-86
  [8]: http://macintoshgarden.org/apps/think-c-scratch
  [9]: http://macintoshgarden.org/apps/macintosh-c-programming-example