# Table of contents | File | Purpose | |--------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------| | [aav.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/aav.d) | An associative array implementation | | [array.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/array.d) | A dynamic array implementation | | [bitarray.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/bitarray.d) | A compact array of bits | | [complex.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/complex.d) | A complex number type | | [ctfloat.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/ctfloat.d) | A floating point type for compile-time calculations | | [env.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/env.d) | Modify environment variables | | [file.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/file.d) | Read a file from disk and store it in memory | | [filename.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/filename.d) | Encapsulate path and file names | | [hash.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/hash.d) | Calculate a hash for a byte array | | [longdouble.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/longdouble.d) | 80-bit floating point number implementation in case they are not natively supported | | [man.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/man.d) | Opens an online manual page | | [optional.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/optional.d) | Implementation of an 'Optional' type | | [port.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/port.d) | Portable routines for functions that have different implementations on different platforms | | [region.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/region.d) | A region allocator | | [response.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/response.d) | Parse command line arguments from response files | | [rmem.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/rmem.d) | Allocate memory using `malloc` or the GC depending on the configuration | | [rootobject.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/rootobject.d) | A root object that classes in dmd inherit from | | [speller.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/speller.d) | Try to detect typos in identifiers | | [string.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/string.d) | Various string related functions | | [stringtable.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/stringtable.d) | Specialized associative array with string keys stored in a variable length structure | | [strtold.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/strtold.d) | D implementation of the standard C function `strtold` (String to long double) | | [utf.d](https://github.com/dlang/dmd/blob/master/compiler/src/dmd/root/utf.d) | Encoding/decoding Unicode text |