Note that the text "Algorithms from P to NP, Volume I", by B.M.E. Moret and H.D. Shapiro, includes full C++ code for a lot of data structures (page numbers are given below under specific structures): binary search trees, skip lists, randomized binary search trees, splay tres, and hash tables (chaining, linear probing, and simple double hashing), all complete, plus tries (both regular and Patricia) and red-black trees (insertion and search only). These routines are likely to be as good as anything you can download, so use them.

For downloading software: some software is archived and compressed into a .zip file (the standard tool in the Windows world) or into a .tar.gz file (the standard tool in the Unix world). In either case, create a new subdirectory and place the archive file there. If the file is a .zip file, type

unzip file.zip
If the file is a .tar.gz file, type
tar xfz file.tar.gz
Be sure to use the tar program in the directory /usr/local/gnu/bin; this is also where you can find the gunzip program to uncompress a .gz file: typing gunzip file.gz will produce file (and also remove the compressed version); if the file is an archive, you can then type tar xf file.tar to extract its content. If you simply type tar on an AIX machine, you will not get the gnu version, but a much older version that does not support the z (compression/decompression) flag. To make sure all of the gnu tools are available to you, put in your path environment the path /usr/local/gnu/bin.
These links are old and some of them are now invalid. They are provided as a starting point for search. Please also check on google for various software libraries.