实现EVC＋＋4.0读取cdb文件。开发环境EVC4.0，已测试通过，测试环境：EVC4.0＋PDA＋WinXPSP2 相关文件请到ESRI和微软网站获取。-achieve EVC + +4.0 read cdb document. EVC4.0 development environment, the test, test environment : EVC4.0 PDA + + WinXPSP2 related documents, visit ESRI and Microsoft