AVL平衡二叉树。原本在这里下载了其他人的平衡二叉树，但发现都不好用，于是从codeguru下载了一个。现在经修正后，已经符合ANSI C规范，并作了适当的封装，用起来和一个类的用法也差不多。这里的代码作为一个demo展示了树的用法。-AVL balanced binary tree. Originally here to download other people s balanced binary tree, but found not easy to use, so from a codeguru download. Now, as amended, has been in line with the ANSI C specification, and made the appropriate package, to use and a similar type of usage. Here as a demo code to display the usage of the tree.