A very good source of scientific programs is Numerical Recipes in C: The Art of Scientific Computing by Press, Teukolsky, Vettering, and Flannery (Cambridge University Press). This book contains the source code and descriptions of many numerical methods commonly used. It is advanced.
If you have have access to C and C++ books which are several years old, please be aware that code which was once acceptable may now generate warnings or errors. (Also, the computational finance code may not compile under old compilers.) The ANSI-C standard was implemented in 1990 to unify C source code, and the ANSI-C++ standard is still evolving. Older books may not be compatible with recent changes to these standards. Several compilers can handle the "old way" of doing things, but they are not required to do so in general.
The Borland-endorsed guide to Turbo C++ is Teach Yourself Turbo C+ 4.5 for Windows in 21 Days by Craig Arnush. In my opinion, the book does not spend enough time describing the basics of the Turbo C++ IDE to be useful for this class. The book has quite a few complete examples, especially in the sections that discuss Windows programming.
There are many Internet locations from which you can download source code for a variety of uses. A good way to find these locations is through a search engine, such as Yahoo in Netscape. Be aware that some source code is written for particular platforms and may not be portable. You should be suspicious of this source code since it generally is not required to be debugged.
The GNU project of the Free Software foundation has ported a large number of UNIX-originated utilities to MS-DOS, such as emacs, vi, ctags, sed, etc. You may be interested in obtaining these utilities if you have used them before in a UNIX setting. Again, Yahoo is a good way of locating these programs. Another good starting point is the ftp site
comp.lang.c++.moderated
comp.std.c++
comp.std.c
comp.lang.c++
comp.lang.c
gnu.g++.help
gnu.g++.announce
but there are probably many more which you will find helpful. If you have problems, you can post questions to an appropriate group. Some of groups are monitored by people who write the C++ compilers for Borland and Microsoft. However, readers of these groups can be quite unforgiving if you ask questions of the wrong group or which are contained in the FAQs (Frequently Asked Questions).